diff --git a/docs/code-style.rst b/docs/code-style.rst
index 2baac21..738e20c 100644
--- a/docs/code-style.rst
+++ b/docs/code-style.rst
@@ -3,11 +3,11 @@
 
 Based on
 
-* "C++ Programming Style Guidelines" by Geotechnical Software Services, Copyright © 1996 – 2011.
-  The original document is available at `<http://geosoft.no/development/cppstyle.html>`_
+* "C++ Programming Style Guidelines" by Geotechnical Software Services, Copyright © 1996-2011.
+  The original document is available at `<http://geosoft.no/development/cppstyle.html>`__
 
 * NDN Platform "C++, C, C#, Java and JavaScript Code Guidelines".
-  The original document is available at `<https://named-data.net/codebase/platform/documentation/ndn-platform-development-guidelines/cpp-code-guidelines/>`_
+  The original document is available at `<https://named-data.net/codebase/platform/documentation/ndn-platform-development-guidelines/cpp-code-guidelines/>`__
 
 1. Code layout
 --------------
@@ -52,11 +52,11 @@
 
         } // namespace example
 
-    Note that code inside namespace is **not** indented. Avoid the following:
+    Note that code inside the namespace is **not** indented. Avoid the following:
 
     .. code-block:: c++
 
-        // NOT
+        // WRONG
         //
         // namespace example {
         //
@@ -479,13 +479,11 @@
 
     .. code-block:: c++
 
-        namespace model {
-        namespace analyzer {
+        namespace model::analyzer {
 
         ...
 
-        } // namespace analyzer
-        } // namespace model
+        } // namespace model::analyzer
 
 2.7. Names representing generic template types should be a single uppercase letter.
 
diff --git a/docs/doxygen.conf.in b/docs/doxygen.conf.in
index c48312c..afcd331 100644
--- a/docs/doxygen.conf.in
+++ b/docs/doxygen.conf.in
@@ -1739,16 +1739,6 @@
 
 LATEX_HIDE_INDICES     = NO
 
-# If the LATEX_SOURCE_CODE tag is set to YES then doxygen will include source
-# code with syntax highlighting in the LaTeX output.
-#
-# Note that which sources are shown also depends on other settings such as
-# SOURCE_BROWSER.
-# The default value is: NO.
-# This tag requires that the tag GENERATE_LATEX is set to YES.
-
-LATEX_SOURCE_CODE      = NO
-
 # The LATEX_BIB_STYLE tag can be used to specify the style to use for the
 # bibliography, e.g. plainnat, or ieeetr. See
 # http://en.wikipedia.org/wiki/BibTeX and \cite for more info.
@@ -1821,16 +1811,6 @@
 
 RTF_EXTENSIONS_FILE    =
 
-# If the RTF_SOURCE_CODE tag is set to YES then doxygen will include source code
-# with syntax highlighting in the RTF output.
-#
-# Note that which sources are shown also depends on other settings such as
-# SOURCE_BROWSER.
-# The default value is: NO.
-# This tag requires that the tag GENERATE_RTF is set to YES.
-
-RTF_SOURCE_CODE        = NO
-
 #---------------------------------------------------------------------------
 # Configuration options related to the man page output
 #---------------------------------------------------------------------------
@@ -1920,15 +1900,6 @@
 
 DOCBOOK_OUTPUT         = docbook
 
-# If the DOCBOOK_PROGRAMLISTING tag is set to YES, doxygen will include the
-# program listings (including syntax highlighting and cross-referencing
-# information) to the DOCBOOK output. Note that enabling this will significantly
-# increase the size of the DOCBOOK output.
-# The default value is: NO.
-# This tag requires that the tag GENERATE_DOCBOOK is set to YES.
-
-DOCBOOK_PROGRAMLISTING = NO
-
 #---------------------------------------------------------------------------
 # Configuration options for the AutoGen Definitions output
 #---------------------------------------------------------------------------
@@ -2119,15 +2090,6 @@
 # Configuration options related to the dot tool
 #---------------------------------------------------------------------------
 
-# If the CLASS_DIAGRAMS tag is set to YES, doxygen will generate a class diagram
-# (in HTML and LaTeX) for classes with base or super classes. Setting the tag to
-# NO turns the diagrams off. Note that this option also works with HAVE_DOT
-# disabled, but it is recommended to install and use dot, since it yields more
-# powerful graphs.
-# The default value is: YES.
-
-CLASS_DIAGRAMS         = YES
-
 # You can include diagrams made with dia in doxygen documentation. Doxygen will
 # then run dia to produce the diagram and insert it in the documentation. The
 # DIA_PATH tag allows you to specify the directory where the dia binary resides.
diff --git a/docs/release-notes/release-notes-0.2.0.rst b/docs/release-notes/release-notes-0.2.0.rst
index 5d804bf..89d7c08 100644
--- a/docs/release-notes/release-notes-0.2.0.rst
+++ b/docs/release-notes/release-notes-0.2.0.rst
@@ -66,7 +66,7 @@
   + Introduce ``util::EventEmitter``, :ndn-cxx:`util::NotificationSubscriber`,
     :ndn-cxx:`util::NotificationStream`, and :ndn-cxx:`nfd::FaceMonitor` utility classes
 
-  + Introduce :ndn-cxx:`util::SegmentFetcher` helper class to fetch multi-segmented data
+  + Introduce :ndn-cxx:`SegmentFetcher` helper class to fetch multi-segmented data
     (:issue:`1879`)
 
 - **Build**
diff --git a/docs/release-notes/release-notes-0.5.1.rst b/docs/release-notes/release-notes-0.5.1.rst
index 8108300..2ba1ec1 100644
--- a/docs/release-notes/release-notes-0.5.1.rst
+++ b/docs/release-notes/release-notes-0.5.1.rst
@@ -63,27 +63,27 @@
 Deprecated
 ^^^^^^^^^^
 
-- Old security framework.  All old security framework classes are moved to
+- Old security framework.  All old security framework classes are moved to the
   ``ndn::security::v1`` namespace in this release and will be removed in the next release.
 
-  * ``v1::KeyChain``, use :ndn-cxx:`v2::KeyChain` instead
+  * ``v1::KeyChain``; use ``v2::KeyChain`` instead.
 
   * ``v1::Validator`` interface and all implementations of this interface (``ValidatorRegex``,
-    ``ValidatorConfig``, ``ValidatorNull``).  Use :ndn-cxx:`v2::Validator` and the
-    corresponding implementations of :ndn-cxx:`ValidationPolicy` interfaces (will be introduced
-    before 0.6.0 release).
+    ``ValidatorConfig``, ``ValidatorNull``).  Use ``v2::Validator`` and the corresponding
+    implementations of :ndn-cxx:`ValidationPolicy` interfaces (will be introduced before
+    the 0.6.0 release).
 
   * ``v1::SecPublicInfo`` and its implementation (``SecPublicInfoSqlite``), ``SecTpm`` and its
     implementations (``SecTpmFile``, ``SecTpmOsx``).  These classes are internal implementation
-    and not intended to be used without ``v1::KeyChain``.  :ndn-cxx:`v2::KeyChain` internally
-    uses the newly introduced :ndn-cxx:`Pib` and :ndn-cxx:`Tpm` interfaces with their
-    corresponding implementations.
+    and not intended to be used without ``v1::KeyChain``.  ``v2::KeyChain`` internally uses
+    the newly introduced :ndn-cxx:`Pib` and :ndn-cxx:`Tpm` interfaces with their corresponding
+    implementations.
 
   * ``v1::Certificate``, ``v1::IdentityCertificate``, ``v1::CertificateExtension``,
-    ``v1::CertificateSubjectDescription``, use :ndn-cxx:`v2::Certificate` and
-    :ndn-cxx:`AdditionalDescription`
+    ``v1::CertificateSubjectDescription``; use ``v2::Certificate`` and ``AdditionalDescription``
+    instead.
 
-  * ``v1::SecuredBag``, use ``v2::SafeBag`` instead
+  * ``v1::SecuredBag``; use :ndn-cxx:`SafeBag` instead.
 
 - Constant ``io::BASE_64``, use ``io::BASE64`` instead (:issue:`3741`)
 
diff --git a/docs/release-notes/release-notes-0.6.0.rst b/docs/release-notes/release-notes-0.6.0.rst
index 904eb1d..f5d7766 100644
--- a/docs/release-notes/release-notes-0.6.0.rst
+++ b/docs/release-notes/release-notes-0.6.0.rst
@@ -102,23 +102,23 @@
 
 - Old security framework.
 
-  * ``v1::KeyChain``, use :ndn-cxx:`v2::KeyChain` instead
+  * ``v1::KeyChain``; use :ndn-cxx:`KeyChain` instead.
 
   * ``v1::Validator`` interface and ``ValidatorRegex`` implementation of this
     interface. ``ValidatorConfig``, ``ValidatorNull`` implementation refactored to be based on
     the new validation framework.
 
   * ``v1::SecPublicInfo`` and its implementation (``SecPublicInfoSqlite``), ``SecTpm`` and its
-    implementations (``SecTpmFile``, ``SecTpmOsx``).  These classes are internal implementation
-    and not intended to be used without ``v1::KeyChain``.  :ndn-cxx:`v2::KeyChain` internally
+    implementations (``SecTpmFile``, ``SecTpmOsx``). These classes are internal implementation
+    and not intended to be used without ``v1::KeyChain``. The new :ndn-cxx:`KeyChain` internally
     uses the newly introduced :ndn-cxx:`Pib` and :ndn-cxx:`Tpm` interfaces with their
     corresponding implementations.
 
   * ``v1::Certificate``, ``v1::IdentityCertificate``, ``v1::CertificateExtension``,
-    ``v1::CertificateSubjectDescription``, use :ndn-cxx:`v2::Certificate` and
-    :ndn-cxx:`AdditionalDescription`
+    ``v1::CertificateSubjectDescription``; use the new :ndn-cxx:`Certificate` and
+    :ndn-cxx:`AdditionalDescription` instead.
 
-  * ``v1::SecuredBag``, use ``v2::SafeBag`` instead
+  * ``v1::SecuredBag``; use :ndn-cxx:`SafeBag` instead.
 
 - Constant ``io::BASE_64``, use ``io::BASE64`` instead (:issue:`3741`)
 
diff --git a/ndn-cxx/detail/asio-fwd.hpp b/ndn-cxx/detail/asio-fwd.hpp
index b90d23b..a0648a1 100644
--- a/ndn-cxx/detail/asio-fwd.hpp
+++ b/ndn-cxx/detail/asio-fwd.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include <boost/version.hpp>
 
-namespace boost {
-namespace asio {
+namespace boost::asio {
 
 #if BOOST_VERSION >= 106600
 class io_context;
@@ -34,7 +33,6 @@
 class io_service;
 #endif // BOOST_VERSION >= 106600
 
-} // namespace asio
-} // namespace boost
+} // namespace boost::asio
 
 #endif // NDN_CXX_DETAIL_ASIO_FWD_HPP
diff --git a/ndn-cxx/detail/cancel-handle.cpp b/ndn-cxx/detail/cancel-handle.cpp
index 4ce807c..b07ecca 100644
--- a/ndn-cxx/detail/cancel-handle.cpp
+++ b/ndn-cxx/detail/cancel-handle.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,8 +21,7 @@
 
 #include "ndn-cxx/detail/cancel-handle.hpp"
 
-namespace ndn {
-namespace detail {
+namespace ndn::detail {
 
 void
 CancelHandle::cancel() const
@@ -33,5 +32,4 @@
   }
 }
 
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail
diff --git a/ndn-cxx/detail/cancel-handle.hpp b/ndn-cxx/detail/cancel-handle.hpp
index a7207a7..65dc110 100644
--- a/ndn-cxx/detail/cancel-handle.hpp
+++ b/ndn-cxx/detail/cancel-handle.hpp
@@ -24,10 +24,13 @@
 
 #include "ndn-cxx/detail/common.hpp"
 
-namespace ndn {
-namespace detail {
+/**
+ * \brief Contains implementation details that are not part of the ndn-cxx public API.
+ */
+namespace ndn::detail {
 
-/** \brief Handle to cancel an operation.
+/**
+ * \brief Handle to cancel an operation.
  */
 class CancelHandle
 {
@@ -52,7 +55,8 @@
 inline
 CancelHandle::CancelHandle() noexcept = default;
 
-/** \brief Cancels an operation automatically upon destruction.
+/**
+ * \brief Cancels an operation automatically upon destruction.
  */
 template<typename HandleT>
 class ScopedCancelHandle
@@ -133,7 +137,6 @@
 template<typename T>
 ScopedCancelHandle<T>::ScopedCancelHandle() noexcept = default;
 
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail
 
 #endif // NDN_CXX_DETAIL_CANCEL_HANDLE_HPP
diff --git a/ndn-cxx/detail/cf-releaser-osx.hpp b/ndn-cxx/detail/cf-releaser-osx.hpp
index 156e7a4..4ff6b66 100644
--- a/ndn-cxx/detail/cf-releaser-osx.hpp
+++ b/ndn-cxx/detail/cf-releaser-osx.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,8 +30,7 @@
 
 #include <CoreFoundation/CoreFoundation.h>
 
-namespace ndn {
-namespace detail {
+namespace ndn::detail {
 
 /**
  * @brief Helper class to wrap CoreFoundation object pointers
@@ -145,7 +144,6 @@
   T m_typeRef;
 };
 
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail
 
 #endif // NDN_CXX_DETAIL_CF_RELEASER_OSX_HPP
diff --git a/ndn-cxx/detail/cf-string-osx.cpp b/ndn-cxx/detail/cf-string-osx.cpp
index 5cceb33..1459f81 100644
--- a/ndn-cxx/detail/cf-string-osx.cpp
+++ b/ndn-cxx/detail/cf-string-osx.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/detail/cf-string-osx.hpp"
 
-namespace ndn {
-namespace detail {
-namespace cfstring {
+namespace ndn::detail::cfstring {
 
 CFReleaser<CFStringRef>
 fromBuffer(const uint8_t* buf, size_t buflen)
@@ -66,6 +64,4 @@
   return str;
 }
 
-} // namespace cfstring
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail::cfstring
diff --git a/ndn-cxx/detail/cf-string-osx.hpp b/ndn-cxx/detail/cf-string-osx.hpp
index 6be2499..4cabdcb 100644
--- a/ndn-cxx/detail/cf-string-osx.hpp
+++ b/ndn-cxx/detail/cf-string-osx.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -36,9 +36,7 @@
  * This file contains utilities to deal with Apple Core Foundation's CFString and related types.
  */
 
-namespace ndn {
-namespace detail {
-namespace cfstring {
+namespace ndn::detail::cfstring {
 
 /**
  * @brief Create a CFString by copying bytes from a raw buffer
@@ -61,8 +59,6 @@
 std::string
 toStdString(CFStringRef cfStr);
 
-} // namespace cfstring
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail::cfstring
 
 #endif // NDN_CXX_DETAIL_CF_STRING_OSX_HPP
diff --git a/ndn-cxx/encoding/block-helpers.cpp b/ndn-cxx/encoding/block-helpers.cpp
index a4b5e8d..bf53c86 100644
--- a/ndn-cxx/encoding/block-helpers.cpp
+++ b/ndn-cxx/encoding/block-helpers.cpp
@@ -23,8 +23,7 @@
 
 #include <boost/endian/conversion.hpp>
 
-namespace ndn {
-namespace encoding {
+namespace ndn::encoding {
 
 namespace endian = boost::endian;
 
@@ -220,5 +219,4 @@
 template size_t
 prependBlock<EncoderTag>(EncodingImpl<EncoderTag>&, const Block&);
 
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::encoding
diff --git a/ndn-cxx/encoding/block.hpp b/ndn-cxx/encoding/block.hpp
index c9cf885..f43d085 100644
--- a/ndn-cxx/encoding/block.hpp
+++ b/ndn-cxx/encoding/block.hpp
@@ -29,11 +29,9 @@
 #include "ndn-cxx/encoding/tlv.hpp"
 #include "ndn-cxx/util/span.hpp"
 
-namespace boost {
-namespace asio {
+namespace boost::asio {
 class const_buffer;
-} // namespace asio
-} // namespace boost
+} // namespace boost::asio
 
 namespace ndn {
 
diff --git a/ndn-cxx/encoding/encoder.cpp b/ndn-cxx/encoding/encoder.cpp
index bd39970..883d272 100644
--- a/ndn-cxx/encoding/encoder.cpp
+++ b/ndn-cxx/encoding/encoder.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include <boost/endian/conversion.hpp>
 
-namespace ndn {
-namespace encoding {
+namespace ndn::encoding {
 
 namespace endian = boost::endian;
 
@@ -200,5 +199,4 @@
   }
 }
 
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::encoding
diff --git a/ndn-cxx/encoding/encoder.hpp b/ndn-cxx/encoding/encoder.hpp
index 7b4e2d8..1d45314 100644
--- a/ndn-cxx/encoding/encoder.hpp
+++ b/ndn-cxx/encoding/encoder.hpp
@@ -26,8 +26,7 @@
 
 #include <algorithm>
 
-namespace ndn {
-namespace encoding {
+namespace ndn::encoding {
 
 /**
  * @brief Helper class to perform TLV encoding.
@@ -278,7 +277,6 @@
   return length;
 }
 
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::encoding
 
 #endif // NDN_CXX_ENCODING_ENCODER_HPP
diff --git a/ndn-cxx/encoding/encoding-buffer.hpp b/ndn-cxx/encoding/encoding-buffer.hpp
index 01471c6..20b8182 100644
--- a/ndn-cxx/encoding/encoding-buffer.hpp
+++ b/ndn-cxx/encoding/encoding-buffer.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,8 +26,7 @@
 #include "ndn-cxx/encoding/encoder.hpp"
 #include "ndn-cxx/encoding/estimator.hpp"
 
-namespace ndn {
-namespace encoding {
+namespace ndn::encoding {
 
 /**
  * @brief EncodingImpl specialization for actual TLV encoding
@@ -62,7 +61,6 @@
   }
 };
 
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::encoding
 
 #endif // NDN_CXX_ENCODING_ENCODING_BUFFER_HPP
diff --git a/ndn-cxx/encoding/estimator.hpp b/ndn-cxx/encoding/estimator.hpp
index 5276a7d..56fa322 100644
--- a/ndn-cxx/encoding/estimator.hpp
+++ b/ndn-cxx/encoding/estimator.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/encoding/block.hpp"
 
-namespace ndn {
-namespace encoding {
+namespace ndn::encoding {
 
 /**
  * @brief Helper class to estimate size of TLV encoding.
@@ -112,7 +111,6 @@
   }
 };
 
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::encoding
 
 #endif // NDN_CXX_ENCODING_ESTIMATOR_HPP
diff --git a/ndn-cxx/encoding/nfd-constants.cpp b/ndn-cxx/encoding/nfd-constants.cpp
index 28c842a..c6f5a58 100644
--- a/ndn-cxx/encoding/nfd-constants.cpp
+++ b/ndn-cxx/encoding/nfd-constants.cpp
@@ -29,8 +29,7 @@
 #include <map>
 #include <ostream>
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 std::ostream&
 operator<<(std::ostream& os, FaceScope faceScope)
@@ -196,5 +195,4 @@
   return os;
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/encoding/nfd-constants.hpp b/ndn-cxx/encoding/nfd-constants.hpp
index 55f1b7b..55e2905 100644
--- a/ndn-cxx/encoding/nfd-constants.hpp
+++ b/ndn-cxx/encoding/nfd-constants.hpp
@@ -26,8 +26,7 @@
 #include <iosfwd>
 #include <limits>
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 inline constexpr uint64_t INVALID_FACE_ID = 0;
 
@@ -131,7 +130,6 @@
 std::ostream&
 operator<<(std::ostream& os, RouteFlags routeFlags);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_ENCODING_NFD_CONSTANTS_HPP
diff --git a/ndn-cxx/encoding/tlv-nfd.hpp b/ndn-cxx/encoding/tlv-nfd.hpp
index 100dd93..f22fd96 100644
--- a/ndn-cxx/encoding/tlv-nfd.hpp
+++ b/ndn-cxx/encoding/tlv-nfd.hpp
@@ -24,9 +24,7 @@
 
 #include <cstdint>
 
-namespace ndn {
-namespace tlv {
-namespace nfd {
+namespace ndn::tlv::nfd {
 
 /**
  * @brief TLV-TYPE numbers defined by the NFD Management protocol.
@@ -105,8 +103,6 @@
   Route    = 129,
 };
 
-} // namespace nfd
-} // namespace tlv
-} // namespace ndn
+} // namespace ndn::tlv::nfd
 
 #endif // NDN_CXX_ENCODING_TLV_NFD_HPP
diff --git a/ndn-cxx/encoding/tlv-security.hpp b/ndn-cxx/encoding/tlv-security.hpp
index be13371..93a11cf 100644
--- a/ndn-cxx/encoding/tlv-security.hpp
+++ b/ndn-cxx/encoding/tlv-security.hpp
@@ -24,9 +24,7 @@
 
 #include <cstdint>
 
-namespace ndn {
-namespace tlv {
-namespace security {
+namespace ndn::tlv::security {
 
 /**
  * @brief TLV-TYPE numbers for SafeBag and related elements.
@@ -37,8 +35,6 @@
   EncryptedKey = 129,
 };
 
-} // namespace security
-} // namespace tlv
-} // namespace ndn
+} // namespace ndn::tlv::security
 
 #endif // NDN_CXX_ENCODING_TLV_SECURITY_HPP
diff --git a/ndn-cxx/encoding/tlv.cpp b/ndn-cxx/encoding/tlv.cpp
index a091914..0487998 100644
--- a/ndn-cxx/encoding/tlv.cpp
+++ b/ndn-cxx/encoding/tlv.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,8 +21,9 @@
 
 #include "ndn-cxx/encoding/tlv.hpp"
 
-namespace ndn {
-namespace tlv {
+#include <ostream>
+
+namespace ndn::tlv {
 
 Error::Error(const char* expectedType, uint32_t actualType)
   : Error("Expecting "s + expectedType + " element, but TLV has type " + to_string(actualType))
@@ -81,5 +82,55 @@
   return os << static_cast<uint32_t>(ct) << ')';
 }
 
-} // namespace tlv
-} // namespace ndn
+size_t
+writeVarNumber(std::ostream& os, uint64_t number)
+{
+  if (number < 253) {
+    os.put(static_cast<char>(number));
+    return 1;
+  }
+  else if (number <= std::numeric_limits<uint16_t>::max()) {
+    os.put(static_cast<char>(253));
+    uint16_t value = boost::endian::native_to_big(static_cast<uint16_t>(number));
+    os.write(reinterpret_cast<const char*>(&value), 2);
+    return 3;
+  }
+  else if (number <= std::numeric_limits<uint32_t>::max()) {
+    os.put(static_cast<char>(254));
+    uint32_t value = boost::endian::native_to_big(static_cast<uint32_t>(number));
+    os.write(reinterpret_cast<const char*>(&value), 4);
+    return 5;
+  }
+  else {
+    os.put(static_cast<char>(255));
+    uint64_t value = boost::endian::native_to_big(number);
+    os.write(reinterpret_cast<const char*>(&value), 8);
+    return 9;
+  }
+}
+
+size_t
+writeNonNegativeInteger(std::ostream& os, uint64_t integer)
+{
+  if (integer <= std::numeric_limits<uint8_t>::max()) {
+    os.put(static_cast<char>(integer));
+    return 1;
+  }
+  else if (integer <= std::numeric_limits<uint16_t>::max()) {
+    uint16_t value = boost::endian::native_to_big(static_cast<uint16_t>(integer));
+    os.write(reinterpret_cast<const char*>(&value), 2);
+    return 2;
+  }
+  else if (integer <= std::numeric_limits<uint32_t>::max()) {
+    uint32_t value = boost::endian::native_to_big(static_cast<uint32_t>(integer));
+    os.write(reinterpret_cast<const char*>(&value), 4);
+    return 4;
+  }
+  else {
+    uint64_t value = boost::endian::native_to_big(integer);
+    os.write(reinterpret_cast<const char*>(&value), 8);
+    return 8;
+  }
+}
+
+} // namespace ndn::tlv
diff --git a/ndn-cxx/encoding/tlv.hpp b/ndn-cxx/encoding/tlv.hpp
index 12bc854..86678ff 100644
--- a/ndn-cxx/encoding/tlv.hpp
+++ b/ndn-cxx/encoding/tlv.hpp
@@ -27,7 +27,6 @@
 #include <cstring>
 #include <iterator>
 #include <limits>
-#include <ostream>
 #include <vector>
 
 #include <boost/endian/conversion.hpp>
@@ -411,33 +410,6 @@
          number <= std::numeric_limits<uint32_t>::max() ? 5 : 9;
 }
 
-inline size_t
-writeVarNumber(std::ostream& os, uint64_t number)
-{
-  if (number < 253) {
-    os.put(static_cast<char>(number));
-    return 1;
-  }
-  else if (number <= std::numeric_limits<uint16_t>::max()) {
-    os.put(static_cast<char>(253));
-    uint16_t value = boost::endian::native_to_big(static_cast<uint16_t>(number));
-    os.write(reinterpret_cast<const char*>(&value), 2);
-    return 3;
-  }
-  else if (number <= std::numeric_limits<uint32_t>::max()) {
-    os.put(static_cast<char>(254));
-    uint32_t value = boost::endian::native_to_big(static_cast<uint32_t>(number));
-    os.write(reinterpret_cast<const char*>(&value), 4);
-    return 5;
-  }
-  else {
-    os.put(static_cast<char>(255));
-    uint64_t value = boost::endian::native_to_big(number);
-    os.write(reinterpret_cast<const char*>(&value), 8);
-    return 9;
-  }
-}
-
 template<typename Iterator>
 constexpr uint64_t
 readNonNegativeInteger(size_t len, Iterator& begin, Iterator end)
@@ -463,30 +435,6 @@
          integer <= std::numeric_limits<uint32_t>::max() ? 4 : 8;
 }
 
-inline size_t
-writeNonNegativeInteger(std::ostream& os, uint64_t integer)
-{
-  if (integer <= std::numeric_limits<uint8_t>::max()) {
-    os.put(static_cast<char>(integer));
-    return 1;
-  }
-  else if (integer <= std::numeric_limits<uint16_t>::max()) {
-    uint16_t value = boost::endian::native_to_big(static_cast<uint16_t>(integer));
-    os.write(reinterpret_cast<const char*>(&value), 2);
-    return 2;
-  }
-  else if (integer <= std::numeric_limits<uint32_t>::max()) {
-    uint32_t value = boost::endian::native_to_big(static_cast<uint32_t>(integer));
-    os.write(reinterpret_cast<const char*>(&value), 4);
-    return 4;
-  }
-  else {
-    uint64_t value = boost::endian::native_to_big(integer);
-    os.write(reinterpret_cast<const char*>(&value), 8);
-    return 8;
-  }
-}
-
 } // namespace tlv
 } // namespace ndn
 
diff --git a/ndn-cxx/impl/face-impl.hpp b/ndn-cxx/impl/face-impl.hpp
index 750e804..54b1ffe 100644
--- a/ndn-cxx/impl/face-impl.hpp
+++ b/ndn-cxx/impl/face-impl.hpp
@@ -35,7 +35,6 @@
 #include "ndn-cxx/transport/unix-transport.hpp"
 #include "ndn-cxx/util/logger.hpp"
 #include "ndn-cxx/util/scheduler.hpp"
-#include "ndn-cxx/util/signal.hpp"
 
 NDN_LOG_INIT(ndn.Face);
 // INFO level: prefix registration, etc.
diff --git a/ndn-cxx/impl/name-component-types.hpp b/ndn-cxx/impl/name-component-types.hpp
index 6f63031..76bb419 100644
--- a/ndn-cxx/impl/name-component-types.hpp
+++ b/ndn-cxx/impl/name-component-types.hpp
@@ -29,8 +29,7 @@
 #include <array>
 #include <unordered_map>
 
-namespace ndn {
-namespace name {
+namespace ndn::name {
 namespace {
 
 /**
@@ -398,7 +397,6 @@
 }
 
 } // namespace
-} // namespace name
-} // namespace ndn
+} // namespace ndn::name
 
 #endif // NDN_CXX_IMPL_NAME_COMPONENT_TYPES_HPP
diff --git a/ndn-cxx/impl/record-container.hpp b/ndn-cxx/impl/record-container.hpp
index 791b0a2..be8a6ef 100644
--- a/ndn-cxx/impl/record-container.hpp
+++ b/ndn-cxx/impl/record-container.hpp
@@ -27,8 +27,7 @@
 
 #include <atomic>
 
-namespace ndn {
-namespace detail {
+namespace ndn::detail {
 
 using RecordId = uint64_t;
 
@@ -92,7 +91,7 @@
   /**
    * \brief Insert a record with given ID.
    */
-  template<typename ...TArgs>
+  template<typename... TArgs>
   Record&
   put(RecordId id, TArgs&&... args)
   {
@@ -115,7 +114,7 @@
   /**
    * \brief Insert a record with newly assigned ID.
    */
-  template<typename ...TArgs>
+  template<typename... TArgs>
   Record&
   insert(TArgs&&... args)
   {
@@ -189,14 +188,13 @@
 public:
   /** \brief Signals when container becomes empty
    */
-  util::Signal<RecordContainer<T>> onEmpty;
+  signal::Signal<RecordContainer<T>> onEmpty;
 
 private:
   Container m_container;
   std::atomic<RecordId> m_lastId{0};
 };
 
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail
 
 #endif // NDN_CXX_IMPL_RECORD_CONTAINER_HPP
diff --git a/ndn-cxx/ims/in-memory-storage-fifo.hpp b/ndn-cxx/ims/in-memory-storage-fifo.hpp
index 50e5cf9..cc59acf 100644
--- a/ndn-cxx/ims/in-memory-storage-fifo.hpp
+++ b/ndn-cxx/ims/in-memory-storage-fifo.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -64,23 +64,20 @@
   class byArrival;
   class byEntity;
 
-  typedef boost::multi_index_container<
+  using CleanupIndex = boost::multi_index_container<
     InMemoryStorageEntry*,
     boost::multi_index::indexed_by<
-
       // by Entry itself
       boost::multi_index::hashed_unique<
         boost::multi_index::tag<byEntity>,
         boost::multi_index::identity<InMemoryStorageEntry*>
       >,
-
       // by arrival (FIFO)
       boost::multi_index::sequenced<
         boost::multi_index::tag<byArrival>
       >
-
     >
-  > CleanupIndex;
+  >;
 
   CleanupIndex m_cleanupIndex;
 };
diff --git a/ndn-cxx/ims/in-memory-storage-lfu.hpp b/ndn-cxx/ims/in-memory-storage-lfu.hpp
index 6c6ebfb..cc8e7dc 100644
--- a/ndn-cxx/ims/in-memory-storage-lfu.hpp
+++ b/ndn-cxx/ims/in-memory-storage-lfu.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -91,25 +91,22 @@
   class byFrequency;
   class byEntity;
 
-  typedef boost::multi_index_container<
+  using CleanupIndex = boost::multi_index_container<
     CleanupEntry,
     boost::multi_index::indexed_by<
-
       // by Entry itself
       boost::multi_index::hashed_unique<
         boost::multi_index::tag<byEntity>,
         boost::multi_index::member<CleanupEntry, InMemoryStorageEntry*, &CleanupEntry::entry>
       >,
-
       // by frequency (LFU)
       boost::multi_index::ordered_non_unique<
         boost::multi_index::tag<byFrequency>,
         boost::multi_index::member<CleanupEntry, uint64_t, &CleanupEntry::frequency>,
         std::less<uint64_t>
       >
-
     >
-  > CleanupIndex;
+  >;
 
   CleanupIndex m_cleanupIndex;
 };
diff --git a/ndn-cxx/ims/in-memory-storage-lru.hpp b/ndn-cxx/ims/in-memory-storage-lru.hpp
index b5524e5..9f0decf 100644
--- a/ndn-cxx/ims/in-memory-storage-lru.hpp
+++ b/ndn-cxx/ims/in-memory-storage-lru.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -73,23 +73,20 @@
   class byUsedTime;
   class byEntity;
 
-  typedef boost::multi_index_container<
+  using CleanupIndex = boost::multi_index_container<
     InMemoryStorageEntry*,
     boost::multi_index::indexed_by<
-
       // by Entry itself
       boost::multi_index::hashed_unique<
         boost::multi_index::tag<byEntity>,
         boost::multi_index::identity<InMemoryStorageEntry*>
       >,
-
       // by last used time (LRU)
       boost::multi_index::sequenced<
         boost::multi_index::tag<byUsedTime>
       >
-
     >
-  > CleanupIndex;
+  >;
 
   CleanupIndex m_cleanupIndex;
 };
diff --git a/ndn-cxx/ims/in-memory-storage.hpp b/ndn-cxx/ims/in-memory-storage.hpp
index 4694e31..2658e4e 100644
--- a/ndn-cxx/ims/in-memory-storage.hpp
+++ b/ndn-cxx/ims/in-memory-storage.hpp
@@ -45,10 +45,9 @@
   // multi_index_container to implement storage
   class byFullName;
 
-  typedef boost::multi_index_container<
+  using Cache = boost::multi_index_container<
     InMemoryStorageEntry*,
     boost::multi_index::indexed_by<
-
       // by Full Name
       boost::multi_index::ordered_unique<
         boost::multi_index::tag<byFullName>,
@@ -56,9 +55,8 @@
                                           &InMemoryStorageEntry::getFullName>,
         std::less<Name>
       >
-
     >
-  > Cache;
+  >;
 
   /** @brief Represents a self-defined const_iterator for the in-memory storage.
    *
diff --git a/ndn-cxx/lp/cache-policy.cpp b/ndn-cxx/lp/cache-policy.cpp
index c64bd04..a460b13 100644
--- a/ndn-cxx/lp/cache-policy.cpp
+++ b/ndn-cxx/lp/cache-policy.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 #include "ndn-cxx/lp/cache-policy.hpp"
 #include "ndn-cxx/encoding/block-helpers.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 std::ostream&
 operator<<(std::ostream& os, CachePolicyType policy)
@@ -132,5 +131,4 @@
   return *this;
 }
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
diff --git a/ndn-cxx/lp/cache-policy.hpp b/ndn-cxx/lp/cache-policy.hpp
index 1b2a436..738fd8e 100644
--- a/ndn-cxx/lp/cache-policy.hpp
+++ b/ndn-cxx/lp/cache-policy.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include "ndn-cxx/encoding/encoding-buffer.hpp"
 #include "ndn-cxx/lp/tlv.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Indicates the cache policy applied to a Data packet.
@@ -101,7 +100,6 @@
 
 NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(CachePolicy);
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_CACHE_POLICY_HPP
diff --git a/ndn-cxx/lp/empty-value.hpp b/ndn-cxx/lp/empty-value.hpp
index 2733d2d..6e20df5 100644
--- a/ndn-cxx/lp/empty-value.hpp
+++ b/ndn-cxx/lp/empty-value.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 #ifndef NDN_CXX_LP_TLV_EMPTY_VALUE_HPP
 #define NDN_CXX_LP_TLV_EMPTY_VALUE_HPP
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Represents a zero-length TLV-VALUE.
@@ -34,7 +33,6 @@
 {
 };
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_TLV_EMPTY_VALUE_HPP
diff --git a/ndn-cxx/lp/field-decl.hpp b/ndn-cxx/lp/field-decl.hpp
index 1cb1916..5fcb3fa 100644
--- a/ndn-cxx/lp/field-decl.hpp
+++ b/ndn-cxx/lp/field-decl.hpp
@@ -29,8 +29,7 @@
 #include <boost/concept/requires.hpp>
 #include <boost/endian/conversion.hpp>
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Indicates that a `uint64_t` field shall be decoded and encoded as a non-negative integer.
@@ -206,7 +205,6 @@
   }
 };
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_FIELD_DECL_HPP
diff --git a/ndn-cxx/lp/field.hpp b/ndn-cxx/lp/field.hpp
index 3ede2b5..3d72fda 100644
--- a/ndn-cxx/lp/field.hpp
+++ b/ndn-cxx/lp/field.hpp
@@ -26,8 +26,7 @@
 
 #include <boost/concept/usage.hpp>
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Indicates where a field may occur.
@@ -67,7 +66,6 @@
   }
 };
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_FIELD_HPP
diff --git a/ndn-cxx/lp/fields.hpp b/ndn-cxx/lp/fields.hpp
index 78444ee..d30ba1f 100644
--- a/ndn-cxx/lp/fields.hpp
+++ b/ndn-cxx/lp/fields.hpp
@@ -33,8 +33,7 @@
 
 #include <boost/mpl/set.hpp>
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Declare the Fragment field.
@@ -134,7 +133,6 @@
   PrefixAnnouncementField
 >;
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_FIELDS_HPP
diff --git a/ndn-cxx/lp/nack-header.cpp b/ndn-cxx/lp/nack-header.cpp
index ab1cc86..71c76ee 100644
--- a/ndn-cxx/lp/nack-header.cpp
+++ b/ndn-cxx/lp/nack-header.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include "ndn-cxx/lp/nack-header.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 std::ostream&
 operator<<(std::ostream& os, NackReason reason)
@@ -138,5 +137,4 @@
   return *this;
 }
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
diff --git a/ndn-cxx/lp/nack-header.hpp b/ndn-cxx/lp/nack-header.hpp
index 6284624..bc78e36 100644
--- a/ndn-cxx/lp/nack-header.hpp
+++ b/ndn-cxx/lp/nack-header.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 #include "ndn-cxx/encoding/encoding-buffer.hpp"
 #include "ndn-cxx/lp/tlv.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Indicates the reason type of a %Network %Nack.
@@ -95,7 +94,6 @@
 
 NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(NackHeader);
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_NACK_HEADER_HPP
diff --git a/ndn-cxx/lp/nack.cpp b/ndn-cxx/lp/nack.cpp
index 7e3a57f..20a0f8f 100644
--- a/ndn-cxx/lp/nack.cpp
+++ b/ndn-cxx/lp/nack.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include "ndn-cxx/lp/nack.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 Nack::Nack() = default;
 
@@ -38,5 +37,4 @@
 {
 }
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
diff --git a/ndn-cxx/lp/nack.hpp b/ndn-cxx/lp/nack.hpp
index e166971..4631130 100644
--- a/ndn-cxx/lp/nack.hpp
+++ b/ndn-cxx/lp/nack.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 #include "ndn-cxx/detail/packet-base.hpp"
 #include "ndn-cxx/lp/nack-header.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Represents a %Network %Nack.
@@ -105,7 +104,6 @@
   NackHeader m_header;
 };
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_NACK_HPP
diff --git a/ndn-cxx/lp/packet.cpp b/ndn-cxx/lp/packet.cpp
index e942acc..be115f9 100644
--- a/ndn-cxx/lp/packet.cpp
+++ b/ndn-cxx/lp/packet.cpp
@@ -25,8 +25,7 @@
 #include <boost/mpl/for_each.hpp>
 #include <boost/range/adaptor/reversed.hpp>
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 namespace {
 
@@ -161,5 +160,4 @@
   return compareFieldSortOrder(FieldInfo(first), FieldInfo(second.type()));
 }
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
diff --git a/ndn-cxx/lp/packet.hpp b/ndn-cxx/lp/packet.hpp
index ba38ebd..9f06555 100644
--- a/ndn-cxx/lp/packet.hpp
+++ b/ndn-cxx/lp/packet.hpp
@@ -24,11 +24,10 @@
 
 #include "ndn-cxx/lp/fields.hpp"
 
-namespace ndn {
 /**
  * @brief Contains classes and functions related to NDNLPv2.
  */
-namespace lp {
+namespace ndn::lp {
 
 class Packet
 {
@@ -208,7 +207,6 @@
   mutable Block m_wire{tlv::LpPacket};
 };
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_PACKET_HPP
diff --git a/ndn-cxx/lp/pit-token.cpp b/ndn-cxx/lp/pit-token.cpp
index f232814..a564dab 100644
--- a/ndn-cxx/lp/pit-token.cpp
+++ b/ndn-cxx/lp/pit-token.cpp
@@ -23,8 +23,7 @@
 #include "ndn-cxx/encoding/tlv.hpp"
 #include "ndn-cxx/util/string-helper.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 constexpr size_t LENGTH_MIN = 1;
 constexpr size_t LENGTH_MAX = 32;
@@ -45,5 +44,4 @@
   return os;
 }
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
diff --git a/ndn-cxx/lp/pit-token.hpp b/ndn-cxx/lp/pit-token.hpp
index 9d0371d..e7e2d12 100644
--- a/ndn-cxx/lp/pit-token.hpp
+++ b/ndn-cxx/lp/pit-token.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/buffer.hpp"
 #include "ndn-cxx/tag.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /** \brief Represent a PIT token field.
  *  \sa https://redmine.named-data.net/projects/nfd/wiki/NDNLPv2#PIT-Token
@@ -67,7 +66,6 @@
 std::ostream&
 operator<<(std::ostream& os, const PitToken& pitToken);
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_PIT_TOKEN_HPP
diff --git a/ndn-cxx/lp/prefix-announcement-header.cpp b/ndn-cxx/lp/prefix-announcement-header.cpp
index 3c5de4d..58ebbc2 100644
--- a/ndn-cxx/lp/prefix-announcement-header.cpp
+++ b/ndn-cxx/lp/prefix-announcement-header.cpp
@@ -22,8 +22,7 @@
 #include "ndn-cxx/lp/prefix-announcement-header.hpp"
 #include "ndn-cxx/lp/tlv.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 PrefixAnnouncementHeader::PrefixAnnouncementHeader() = default;
 
@@ -67,5 +66,4 @@
   wire.parse();
   m_prefixAnn.emplace(Data(wire.get(ndn::tlv::Data)));
 }
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
diff --git a/ndn-cxx/lp/prefix-announcement-header.hpp b/ndn-cxx/lp/prefix-announcement-header.hpp
index 59e4cc9..f236039 100644
--- a/ndn-cxx/lp/prefix-announcement-header.hpp
+++ b/ndn-cxx/lp/prefix-announcement-header.hpp
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/prefix-announcement.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /** \brief Represents a PrefixAnnouncement header field in NDNLP.
  */
@@ -73,7 +72,6 @@
 
 NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(PrefixAnnouncementHeader);
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_PREFIX_ANNOUNCEMENT_HEADER_HPP
diff --git a/ndn-cxx/lp/sequence.hpp b/ndn-cxx/lp/sequence.hpp
index 4b662dd..919db36 100644
--- a/ndn-cxx/lp/sequence.hpp
+++ b/ndn-cxx/lp/sequence.hpp
@@ -26,15 +26,13 @@
 
 #include <cstdint>
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \brief Represents a sequence number.
  */
 using Sequence = uint64_t;
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_SEQUENCE_HPP
diff --git a/ndn-cxx/lp/tags.hpp b/ndn-cxx/lp/tags.hpp
index b32bc60..312a39d 100644
--- a/ndn-cxx/lp/tags.hpp
+++ b/ndn-cxx/lp/tags.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include "ndn-cxx/lp/prefix-announcement-header.hpp"
 #include "ndn-cxx/tag.hpp"
 
-namespace ndn {
-namespace lp {
+namespace ndn::lp {
 
 /**
  * \class IncomingFaceIdTag
@@ -78,7 +77,6 @@
  */
 using PrefixAnnouncementTag = SimpleTag<PrefixAnnouncementHeader, 15>;
 
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp
 
 #endif // NDN_CXX_LP_TAGS_HPP
diff --git a/ndn-cxx/lp/tlv.hpp b/ndn-cxx/lp/tlv.hpp
index fe99f34..10fe1f6 100644
--- a/ndn-cxx/lp/tlv.hpp
+++ b/ndn-cxx/lp/tlv.hpp
@@ -24,12 +24,10 @@
 
 #include <cstdint>
 
-namespace ndn {
-namespace lp {
 /**
  * @brief Contains constants related to the NDNLPv2 packet format.
  */
-namespace tlv {
+namespace ndn::lp::tlv {
 
 /**
  * @brief TLV-TYPE numbers for NDNLPv2.
@@ -72,8 +70,6 @@
   HEADER3_MAX = 959,
 };
 
-} // namespace tlv
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::lp::tlv
 
 #endif // NDN_CXX_LP_TLV_HPP
diff --git a/ndn-cxx/mgmt/control-parameters.hpp b/ndn-cxx/mgmt/control-parameters.hpp
index 382a7af..211ca53 100644
--- a/ndn-cxx/mgmt/control-parameters.hpp
+++ b/ndn-cxx/mgmt/control-parameters.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/encoding/block.hpp"
 
-namespace ndn {
-namespace mgmt {
+namespace ndn::mgmt {
 
 /**
  * \brief Base class for a struct that contains ControlCommand parameters.
@@ -43,7 +42,6 @@
   wireEncode() const = 0;
 };
 
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::mgmt
 
 #endif // NDN_CXX_MGMT_CONTROL_PARAMETERS_HPP
diff --git a/ndn-cxx/mgmt/control-response.cpp b/ndn-cxx/mgmt/control-response.cpp
index ce0b0da..ffff61a 100644
--- a/ndn-cxx/mgmt/control-response.cpp
+++ b/ndn-cxx/mgmt/control-response.cpp
@@ -23,8 +23,7 @@
 #include "ndn-cxx/encoding/block-helpers.hpp"
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 
-namespace ndn {
-namespace mgmt {
+namespace ndn::mgmt {
 
 ControlResponse::ControlResponse() = default;
 
@@ -110,5 +109,4 @@
     m_body = {};
 }
 
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::mgmt
diff --git a/ndn-cxx/mgmt/control-response.hpp b/ndn-cxx/mgmt/control-response.hpp
index 981384f8..11804de 100644
--- a/ndn-cxx/mgmt/control-response.hpp
+++ b/ndn-cxx/mgmt/control-response.hpp
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/encoding/block.hpp"
 
-namespace ndn {
-namespace mgmt {
+namespace ndn::mgmt {
 
 /**
  * \brief ControlCommand response.
@@ -97,7 +96,6 @@
   }
 };
 
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::mgmt
 
 #endif // NDN_CXX_MGMT_CONTROL_RESPONSE_HPP
diff --git a/ndn-cxx/mgmt/dispatcher.cpp b/ndn-cxx/mgmt/dispatcher.cpp
index 4a2079d..a192642 100644
--- a/ndn-cxx/mgmt/dispatcher.cpp
+++ b/ndn-cxx/mgmt/dispatcher.cpp
@@ -25,10 +25,9 @@
 
 #include <algorithm>
 
-NDN_LOG_INIT(ndn.mgmt.Dispatcher);
+namespace ndn::mgmt {
 
-namespace ndn {
-namespace mgmt {
+NDN_LOG_INIT(ndn.mgmt.Dispatcher);
 
 Authorization
 makeAcceptAllAuthorization()
@@ -343,5 +342,4 @@
   sendData(streamName, notification, {}, SendDestination::FACE_AND_IMS);
 }
 
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::mgmt
diff --git a/ndn-cxx/mgmt/dispatcher.hpp b/ndn-cxx/mgmt/dispatcher.hpp
index 3cc9092..9c5bdde 100644
--- a/ndn-cxx/mgmt/dispatcher.hpp
+++ b/ndn-cxx/mgmt/dispatcher.hpp
@@ -32,8 +32,7 @@
 
 #include <unordered_map>
 
-namespace ndn {
-namespace mgmt {
+namespace ndn::mgmt {
 
 // ---- AUTHORIZATION ----
 
@@ -488,7 +487,6 @@
   };
 }
 
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::mgmt
 
 #endif // NDN_CXX_MGMT_DISPATCHER_HPP
diff --git a/ndn-cxx/mgmt/nfd/channel-status.cpp b/ndn-cxx/mgmt/nfd/channel-status.cpp
index f39f11a..d8882af 100644
--- a/ndn-cxx/mgmt/nfd/channel-status.cpp
+++ b/ndn-cxx/mgmt/nfd/channel-status.cpp
@@ -23,8 +23,7 @@
 #include "ndn-cxx/encoding/block-helpers.hpp"
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 ChannelStatus::ChannelStatus() = default;
 
@@ -102,5 +101,4 @@
   return os << "Channel(LocalUri: " << status.getLocalUri() << ")";
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/channel-status.hpp b/ndn-cxx/mgmt/nfd/channel-status.hpp
index 4fbc06b..f2a896c 100644
--- a/ndn-cxx/mgmt/nfd/channel-status.hpp
+++ b/ndn-cxx/mgmt/nfd/channel-status.hpp
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/encoding/block.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -86,7 +85,6 @@
 std::ostream&
 operator<<(std::ostream& os, const ChannelStatus& status);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_CHANNEL_STATUS_HPP
diff --git a/ndn-cxx/mgmt/nfd/command-options.cpp b/ndn-cxx/mgmt/nfd/command-options.cpp
index 36faba2..921e822 100644
--- a/ndn-cxx/mgmt/nfd/command-options.cpp
+++ b/ndn-cxx/mgmt/nfd/command-options.cpp
@@ -21,8 +21,7 @@
 
 #include "ndn-cxx/mgmt/nfd/command-options.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 CommandOptions&
 CommandOptions::setTimeout(time::milliseconds timeout)
@@ -48,5 +47,4 @@
   return *this;
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/command-options.hpp b/ndn-cxx/mgmt/nfd/command-options.hpp
index 5a341fe..e4ad172 100644
--- a/ndn-cxx/mgmt/nfd/command-options.hpp
+++ b/ndn-cxx/mgmt/nfd/command-options.hpp
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/security/signing-info.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -106,7 +105,6 @@
   security::SigningInfo m_signingInfo;
 };
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_COMMAND_OPTIONS_HPP
diff --git a/ndn-cxx/mgmt/nfd/control-command.cpp b/ndn-cxx/mgmt/nfd/control-command.cpp
index a6daa76..352fa4c 100644
--- a/ndn-cxx/mgmt/nfd/control-command.cpp
+++ b/ndn-cxx/mgmt/nfd/control-command.cpp
@@ -21,8 +21,7 @@
 
 #include "ndn-cxx/mgmt/nfd/control-command.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 ControlCommand::ControlCommand(const std::string& module, const std::string& verb)
   : m_module(module)
@@ -419,5 +418,4 @@
   }
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/control-command.hpp b/ndn-cxx/mgmt/nfd/control-command.hpp
index 9aa5820..a01c9a9 100644
--- a/ndn-cxx/mgmt/nfd/control-command.hpp
+++ b/ndn-cxx/mgmt/nfd/control-command.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/mgmt/nfd/control-parameters.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -319,7 +318,6 @@
   validateResponse(const ControlParameters& parameters) const override;
 };
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_CONTROL_COMMAND_HPP
diff --git a/ndn-cxx/mgmt/nfd/control-parameters.cpp b/ndn-cxx/mgmt/nfd/control-parameters.cpp
index 9ec7234..4e8c866 100644
--- a/ndn-cxx/mgmt/nfd/control-parameters.cpp
+++ b/ndn-cxx/mgmt/nfd/control-parameters.cpp
@@ -24,8 +24,7 @@
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 #include "ndn-cxx/util/string-helper.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 ControlParameters::ControlParameters()
   : m_hasFields(CONTROL_PARAMETER_UBOUND)
@@ -379,5 +378,4 @@
   return os;
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/control-parameters.hpp b/ndn-cxx/mgmt/nfd/control-parameters.hpp
index 18e5534..b49ba4f 100644
--- a/ndn-cxx/mgmt/nfd/control-parameters.hpp
+++ b/ndn-cxx/mgmt/nfd/control-parameters.hpp
@@ -27,8 +27,7 @@
 #include "ndn-cxx/mgmt/control-parameters.hpp"
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -662,7 +661,6 @@
 std::ostream&
 operator<<(std::ostream& os, const ControlParameters& parameters);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_CONTROL_PARAMETERS_HPP
diff --git a/ndn-cxx/mgmt/nfd/control-response.hpp b/ndn-cxx/mgmt/nfd/control-response.hpp
index f02f4db..c7effc3 100644
--- a/ndn-cxx/mgmt/nfd/control-response.hpp
+++ b/ndn-cxx/mgmt/nfd/control-response.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,12 +24,10 @@
 
 #include "ndn-cxx/mgmt/control-response.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 using ControlResponse = mgmt::ControlResponse;
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_CONTROL_RESPONSE_HPP
diff --git a/ndn-cxx/mgmt/nfd/controller.cpp b/ndn-cxx/mgmt/nfd/controller.cpp
index 38a0052..4cc2fa8 100644
--- a/ndn-cxx/mgmt/nfd/controller.cpp
+++ b/ndn-cxx/mgmt/nfd/controller.cpp
@@ -25,10 +25,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-
-using ndn::util::SegmentFetcher;
+namespace ndn::nfd {
 
 Controller::Controller(Face& face, KeyChain& keyChain, security::Validator& validator)
   : m_face(face)
@@ -184,5 +181,4 @@
   }
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/controller.hpp b/ndn-cxx/mgmt/nfd/controller.hpp
index d0d3f08..b9adc75 100644
--- a/ndn-cxx/mgmt/nfd/controller.hpp
+++ b/ndn-cxx/mgmt/nfd/controller.hpp
@@ -34,6 +34,9 @@
 
 class Face;
 
+/**
+ * @brief Contains classes and functions related to the NFD Management protocol.
+ */
 namespace nfd {
 
 /**
@@ -178,7 +181,7 @@
   security::InterestSigner m_signer;
 
 NDN_CXX_PUBLIC_WITH_TESTS_ELSE_PROTECTED:
-  std::set<shared_ptr<util::SegmentFetcher>> m_fetchers;
+  std::set<shared_ptr<SegmentFetcher>> m_fetchers;
 };
 
 template<typename Dataset>
diff --git a/ndn-cxx/mgmt/nfd/cs-info.cpp b/ndn-cxx/mgmt/nfd/cs-info.cpp
index cfae566..e855d73 100644
--- a/ndn-cxx/mgmt/nfd/cs-info.cpp
+++ b/ndn-cxx/mgmt/nfd/cs-info.cpp
@@ -24,8 +24,7 @@
 #include "ndn-cxx/encoding/encoding-buffer.hpp"
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 CsInfo::CsInfo() = default;
 
@@ -190,5 +189,4 @@
             << csi.getNMisses() << (csi.getNMisses() == 1 ? " miss" : " misses");
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/cs-info.hpp b/ndn-cxx/mgmt/nfd/cs-info.hpp
index 541c08c..9103c8f 100644
--- a/ndn-cxx/mgmt/nfd/cs-info.hpp
+++ b/ndn-cxx/mgmt/nfd/cs-info.hpp
@@ -27,8 +27,7 @@
 
 #include <bitset>
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /** \ingroup management
  *  \brief Represents the CS Information dataset.
@@ -150,7 +149,6 @@
 std::ostream&
 operator<<(std::ostream& os, const CsInfo& csi);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_CS_INFO_HPP
diff --git a/ndn-cxx/mgmt/nfd/face-event-notification.cpp b/ndn-cxx/mgmt/nfd/face-event-notification.cpp
index de5dc40..5c19a92 100644
--- a/ndn-cxx/mgmt/nfd/face-event-notification.cpp
+++ b/ndn-cxx/mgmt/nfd/face-event-notification.cpp
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 #include "ndn-cxx/util/string-helper.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 FaceEventNotification::FaceEventNotification() = default;
 
@@ -185,5 +184,4 @@
   return os << "          )";
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/face-event-notification.hpp b/ndn-cxx/mgmt/nfd/face-event-notification.hpp
index 959cf93..8702b40 100644
--- a/ndn-cxx/mgmt/nfd/face-event-notification.hpp
+++ b/ndn-cxx/mgmt/nfd/face-event-notification.hpp
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/mgmt/nfd/face-traits.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -84,7 +83,6 @@
 std::ostream&
 operator<<(std::ostream& os, const FaceEventNotification& notification);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_FACE_EVENT_NOTIFICATION_HPP
diff --git a/ndn-cxx/mgmt/nfd/face-monitor.hpp b/ndn-cxx/mgmt/nfd/face-monitor.hpp
index 07fefd8..3ed6579 100644
--- a/ndn-cxx/mgmt/nfd/face-monitor.hpp
+++ b/ndn-cxx/mgmt/nfd/face-monitor.hpp
@@ -31,8 +31,7 @@
 #include "ndn-cxx/mgmt/nfd/face-event-notification.hpp"
 #include "ndn-cxx/util/notification-subscriber.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \brief A subscriber for the %Face status change notification stream.
@@ -48,7 +47,6 @@
   }
 };
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_FACE_MONITOR_HPP
diff --git a/ndn-cxx/mgmt/nfd/face-query-filter.cpp b/ndn-cxx/mgmt/nfd/face-query-filter.cpp
index 1cf2d5c..dbdb2f9 100644
--- a/ndn-cxx/mgmt/nfd/face-query-filter.cpp
+++ b/ndn-cxx/mgmt/nfd/face-query-filter.cpp
@@ -23,8 +23,7 @@
 #include "ndn-cxx/encoding/block-helpers.hpp"
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 FaceQueryFilter::FaceQueryFilter() = default;
 
@@ -336,5 +335,4 @@
   return os;
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/face-query-filter.hpp b/ndn-cxx/mgmt/nfd/face-query-filter.hpp
index 65de800..a09f405 100644
--- a/ndn-cxx/mgmt/nfd/face-query-filter.hpp
+++ b/ndn-cxx/mgmt/nfd/face-query-filter.hpp
@@ -27,8 +27,7 @@
 
 #include <optional>
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -230,7 +229,6 @@
 std::ostream&
 operator<<(std::ostream& os, const FaceQueryFilter& filter);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_FACE_QUERY_FILTER_HPP
diff --git a/ndn-cxx/mgmt/nfd/face-status.cpp b/ndn-cxx/mgmt/nfd/face-status.cpp
index 04b4bdb..4ab55fe 100644
--- a/ndn-cxx/mgmt/nfd/face-status.cpp
+++ b/ndn-cxx/mgmt/nfd/face-status.cpp
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 #include "ndn-cxx/util/string-helper.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 FaceStatus::FaceStatus() = default;
 
@@ -460,5 +459,4 @@
   return os << "     )";
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/face-status.hpp b/ndn-cxx/mgmt/nfd/face-status.hpp
index 7cd9da3..fa49c8f 100644
--- a/ndn-cxx/mgmt/nfd/face-status.hpp
+++ b/ndn-cxx/mgmt/nfd/face-status.hpp
@@ -27,8 +27,7 @@
 
 #include <optional>
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -249,7 +248,6 @@
 std::ostream&
 operator<<(std::ostream& os, const FaceStatus& status);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_FACE_STATUS_HPP
diff --git a/ndn-cxx/mgmt/nfd/face-traits.hpp b/ndn-cxx/mgmt/nfd/face-traits.hpp
index d497b4d..7816665 100644
--- a/ndn-cxx/mgmt/nfd/face-traits.hpp
+++ b/ndn-cxx/mgmt/nfd/face-traits.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/block.hpp"
 #include "ndn-cxx/encoding/nfd-constants.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -191,7 +190,6 @@
   mutable Block m_wire;
 };
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_FACE_TRAITS_HPP
diff --git a/ndn-cxx/mgmt/nfd/fib-entry.cpp b/ndn-cxx/mgmt/nfd/fib-entry.cpp
index d2c4f5a..c45e888 100644
--- a/ndn-cxx/mgmt/nfd/fib-entry.cpp
+++ b/ndn-cxx/mgmt/nfd/fib-entry.cpp
@@ -27,8 +27,7 @@
 
 #include <boost/range/adaptor/reversed.hpp>
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 NextHopRecord::NextHopRecord() = default;
 
@@ -264,5 +263,4 @@
   return os << "         )";
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/fib-entry.hpp b/ndn-cxx/mgmt/nfd/fib-entry.hpp
index b68071d..a0e5e36 100644
--- a/ndn-cxx/mgmt/nfd/fib-entry.hpp
+++ b/ndn-cxx/mgmt/nfd/fib-entry.hpp
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/nfd-constants.hpp"
 #include "ndn-cxx/name.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /** \ingroup management
  *  \sa https://redmine.named-data.net/projects/nfd/wiki/FibMgmt#FIB-Dataset
@@ -173,7 +172,6 @@
 std::ostream&
 operator<<(std::ostream& os, const FibEntry& entry);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_FIB_ENTRY_HPP
diff --git a/ndn-cxx/mgmt/nfd/forwarder-status.cpp b/ndn-cxx/mgmt/nfd/forwarder-status.cpp
index 09b3971..a92bfc2 100644
--- a/ndn-cxx/mgmt/nfd/forwarder-status.cpp
+++ b/ndn-cxx/mgmt/nfd/forwarder-status.cpp
@@ -24,8 +24,7 @@
 #include "ndn-cxx/encoding/encoding-buffer.hpp"
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 ForwarderStatus::ForwarderStatus() = default;
 
@@ -231,7 +230,7 @@
 }
 
 ForwarderStatus&
-ForwarderStatus::setStartTimestamp(const time::system_clock::TimePoint& startTimestamp)
+ForwarderStatus::setStartTimestamp(const time::system_clock::time_point& startTimestamp)
 {
   m_wire.reset();
   m_startTimestamp = startTimestamp;
@@ -239,7 +238,7 @@
 }
 
 ForwarderStatus&
-ForwarderStatus::setCurrentTimestamp(const time::system_clock::TimePoint& currentTimestamp)
+ForwarderStatus::setCurrentTimestamp(const time::system_clock::time_point& currentTimestamp)
 {
   m_wire.reset();
   m_currentTimestamp = currentTimestamp;
@@ -395,5 +394,4 @@
   return os;
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/forwarder-status.hpp b/ndn-cxx/mgmt/nfd/forwarder-status.hpp
index e010732..70ea5ba 100644
--- a/ndn-cxx/mgmt/nfd/forwarder-status.hpp
+++ b/ndn-cxx/mgmt/nfd/forwarder-status.hpp
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/block.hpp"
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -249,7 +248,6 @@
 std::ostream&
 operator<<(std::ostream& os, const ForwarderStatus& status);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_FORWARDER_STATUS_HPP
diff --git a/ndn-cxx/mgmt/nfd/rib-entry.cpp b/ndn-cxx/mgmt/nfd/rib-entry.cpp
index 73e7f43..cd8e74b 100644
--- a/ndn-cxx/mgmt/nfd/rib-entry.cpp
+++ b/ndn-cxx/mgmt/nfd/rib-entry.cpp
@@ -28,8 +28,7 @@
 
 #include <boost/range/adaptor/reversed.hpp>
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 Route::Route() = default;
 
@@ -341,5 +340,4 @@
   return os << "         )";
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/rib-entry.hpp b/ndn-cxx/mgmt/nfd/rib-entry.hpp
index 24eb78b..4de95d7 100644
--- a/ndn-cxx/mgmt/nfd/rib-entry.hpp
+++ b/ndn-cxx/mgmt/nfd/rib-entry.hpp
@@ -27,8 +27,7 @@
 #include "ndn-cxx/name.hpp"
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -225,7 +224,6 @@
 std::ostream&
 operator<<(std::ostream& os, const RibEntry& entry);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_RIB_ENTRY_HPP
diff --git a/ndn-cxx/mgmt/nfd/route-flags-traits.hpp b/ndn-cxx/mgmt/nfd/route-flags-traits.hpp
index be7553e..160a266 100644
--- a/ndn-cxx/mgmt/nfd/route-flags-traits.hpp
+++ b/ndn-cxx/mgmt/nfd/route-flags-traits.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/encoding/nfd-constants.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -54,7 +53,6 @@
   RouteFlagsTraits() = default;
 };
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_ROUTE_FLAGS_TRAITS_HPP
diff --git a/ndn-cxx/mgmt/nfd/status-dataset.cpp b/ndn-cxx/mgmt/nfd/status-dataset.cpp
index fe8b178..139ff89 100644
--- a/ndn-cxx/mgmt/nfd/status-dataset.cpp
+++ b/ndn-cxx/mgmt/nfd/status-dataset.cpp
@@ -21,8 +21,7 @@
 
 #include "ndn-cxx/mgmt/nfd/status-dataset.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 Name
 StatusDatasetBase::getDatasetPrefix(const Name& prefix) const
@@ -158,5 +157,4 @@
   return parseDatasetVector<RibEntry>(payload);
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/status-dataset.hpp b/ndn-cxx/mgmt/nfd/status-dataset.hpp
index 93cc331..8bddf15 100644
--- a/ndn-cxx/mgmt/nfd/status-dataset.hpp
+++ b/ndn-cxx/mgmt/nfd/status-dataset.hpp
@@ -32,8 +32,7 @@
 #include "ndn-cxx/mgmt/nfd/strategy-choice.hpp"
 #include "ndn-cxx/mgmt/nfd/rib-entry.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \brief Exception raised when the fetched payload cannot be parsed as a StatusDataset.
@@ -211,7 +210,6 @@
   parseResult(ConstBufferPtr payload) const;
 };
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_STATUS_DATASET_HPP
diff --git a/ndn-cxx/mgmt/nfd/strategy-choice.cpp b/ndn-cxx/mgmt/nfd/strategy-choice.cpp
index 6ef45c5..cf13c3f 100644
--- a/ndn-cxx/mgmt/nfd/strategy-choice.cpp
+++ b/ndn-cxx/mgmt/nfd/strategy-choice.cpp
@@ -24,8 +24,7 @@
 #include "ndn-cxx/encoding/encoding-buffer.hpp"
 #include "ndn-cxx/encoding/tlv-nfd.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 StrategyChoice::StrategyChoice() = default;
 
@@ -131,5 +130,4 @@
             << ")";
 }
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
diff --git a/ndn-cxx/mgmt/nfd/strategy-choice.hpp b/ndn-cxx/mgmt/nfd/strategy-choice.hpp
index 59db5ba..fba108e 100644
--- a/ndn-cxx/mgmt/nfd/strategy-choice.hpp
+++ b/ndn-cxx/mgmt/nfd/strategy-choice.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/block.hpp"
 #include "ndn-cxx/name.hpp"
 
-namespace ndn {
-namespace nfd {
+namespace ndn::nfd {
 
 /**
  * \ingroup management
@@ -97,7 +96,6 @@
 std::ostream&
 operator<<(std::ostream& os, const StrategyChoice& sc);
 
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::nfd
 
 #endif // NDN_CXX_MGMT_NFD_STRATEGY_CHOICE_HPP
diff --git a/ndn-cxx/mgmt/status-dataset-context.cpp b/ndn-cxx/mgmt/status-dataset-context.cpp
index 0848a05..4e0de69 100644
--- a/ndn-cxx/mgmt/status-dataset-context.cpp
+++ b/ndn-cxx/mgmt/status-dataset-context.cpp
@@ -21,8 +21,7 @@
 
 #include "ndn-cxx/mgmt/status-dataset-context.hpp"
 
-namespace ndn {
-namespace mgmt {
+namespace ndn::mgmt {
 
 constexpr size_t MAX_PAYLOAD_LENGTH = MAX_NDN_PACKET_SIZE - 800;
 
@@ -106,5 +105,4 @@
   m_nackSender(resp);
 }
 
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::mgmt
diff --git a/ndn-cxx/mgmt/status-dataset-context.hpp b/ndn-cxx/mgmt/status-dataset-context.hpp
index 7eb5dcb..643cbd1 100644
--- a/ndn-cxx/mgmt/status-dataset-context.hpp
+++ b/ndn-cxx/mgmt/status-dataset-context.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include "ndn-cxx/interest.hpp"
 #include "ndn-cxx/mgmt/control-response.hpp"
 
-namespace ndn {
-namespace mgmt {
+namespace ndn::mgmt {
 
 /**
  * \brief Provides a context for generating the response to a StatusDataset request.
@@ -109,7 +108,6 @@
   State m_state = State::INITIAL;
 };
 
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::mgmt
 
 #endif // NDN_CXX_MGMT_STATUS_DATASET_CONTEXT_HPP
diff --git a/ndn-cxx/name-component.cpp b/ndn-cxx/name-component.cpp
index abedc2c..964353e 100644
--- a/ndn-cxx/name-component.cpp
+++ b/ndn-cxx/name-component.cpp
@@ -32,8 +32,7 @@
 
 #include <boost/logic/tribool.hpp>
 
-namespace ndn {
-namespace name {
+namespace ndn::name {
 
 static Convention g_conventionEncoding = Convention::TYPED;
 static Convention g_conventionDecoding = Convention::EITHER;
@@ -510,5 +509,4 @@
   // validity check is done within Component(const Block& wire)
 }
 
-} // namespace name
-} // namespace ndn
+} // namespace ndn::name
diff --git a/ndn-cxx/name-component.hpp b/ndn-cxx/name-component.hpp
index 839b46e..9b245c1 100644
--- a/ndn-cxx/name-component.hpp
+++ b/ndn-cxx/name-component.hpp
@@ -26,8 +26,7 @@
 #include "ndn-cxx/encoding/block-helpers.hpp"
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace name {
+namespace ndn::name {
 
 /**
  * @brief Format used for the URI representation of a name.
@@ -592,7 +591,6 @@
 
 NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(Component);
 
-} // namespace name
-} // namespace ndn
+} // namespace ndn::name
 
 #endif // NDN_CXX_NAME_COMPONENT_HPP
diff --git a/ndn-cxx/net/dns.cpp b/ndn-cxx/net/dns.cpp
index 9b0a9f1..5303e93 100644
--- a/ndn-cxx/net/dns.cpp
+++ b/ndn-cxx/net/dns.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 #include <boost/asio/post.hpp>
 #endif
 
-namespace ndn {
-namespace dns {
+namespace ndn::dns {
 
 class Resolver : noncopyable
 {
@@ -169,5 +168,4 @@
   return it->endpoint().address();
 }
 
-} // namespace dns
-} // namespace ndn
+} // namespace ndn::dns
diff --git a/ndn-cxx/net/dns.hpp b/ndn-cxx/net/dns.hpp
index a2db537..4859d98 100644
--- a/ndn-cxx/net/dns.hpp
+++ b/ndn-cxx/net/dns.hpp
@@ -27,8 +27,7 @@
 
 #include <boost/asio/ip/address.hpp>
 
-namespace ndn {
-namespace dns {
+namespace ndn::dns {
 
 using IpAddress = boost::asio::ip::address;
 using AddressSelector = std::function<bool(const IpAddress&)>;
@@ -109,7 +108,6 @@
             boost::asio::io_service& ioService,
             const AddressSelector& addressSelector = AnyAddress());
 
-} // namespace dns
-} // namespace ndn
+} // namespace ndn::dns
 
 #endif // NDN_CXX_NET_DNS_HPP
diff --git a/ndn-cxx/net/ethernet.cpp b/ndn-cxx/net/ethernet.cpp
index cced947..9848657 100644
--- a/ndn-cxx/net/ethernet.cpp
+++ b/ndn-cxx/net/ethernet.cpp
@@ -34,8 +34,7 @@
 #include <cstdio>
 #include <ostream>
 
-namespace ndn {
-namespace ethernet {
+namespace ndn::ethernet {
 
 Address::Address()
 {
@@ -130,8 +129,7 @@
   return o << a.toString();
 }
 
-} // namespace ethernet
-} // namespace ndn
+} // namespace ndn::ethernet
 
 std::size_t
 std::hash<ndn::ethernet::Address>::operator()(const ndn::ethernet::Address& a) const noexcept
diff --git a/ndn-cxx/net/ethernet.hpp b/ndn-cxx/net/ethernet.hpp
index 62b233c..9edddd8 100644
--- a/ndn-cxx/net/ethernet.hpp
+++ b/ndn-cxx/net/ethernet.hpp
@@ -33,8 +33,7 @@
 #include <functional>
 #include <string>
 
-namespace ndn {
-namespace ethernet {
+namespace ndn::ethernet {
 
 inline constexpr uint16_t ETHERTYPE_NDN = 0x8624; ///< The NDN Ethertype
 
@@ -110,8 +109,7 @@
 std::ostream&
 operator<<(std::ostream& o, const Address& a);
 
-} // namespace ethernet
-} // namespace ndn
+} // namespace ndn::ethernet
 
 namespace std {
 
diff --git a/ndn-cxx/net/impl/link-type-helper-osx.mm b/ndn-cxx/net/impl/link-type-helper-osx.mm
index 7512259..f752b24 100644
--- a/ndn-cxx/net/impl/link-type-helper-osx.mm
+++ b/ndn-cxx/net/impl/link-type-helper-osx.mm
@@ -31,9 +31,7 @@
 #import <CoreWLAN/CWInterface.h>
 #import <CoreWLAN/CWWiFiClient.h>
 
-namespace ndn {
-namespace net {
-namespace detail {
+namespace ndn::net::detail {
 
 ndn::nfd::LinkType
 getLinkType(const std::string& ifName)
@@ -61,6 +59,4 @@
   }
 }
 
-} // namespace detail
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net::detail
diff --git a/ndn-cxx/net/impl/link-type-helper.cpp b/ndn-cxx/net/impl/link-type-helper.cpp
index 6ad4059..018af82 100644
--- a/ndn-cxx/net/impl/link-type-helper.cpp
+++ b/ndn-cxx/net/impl/link-type-helper.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 // implemented in link-type-helper-osx.mm
 #else
 
-namespace ndn {
-namespace net {
-namespace detail {
+namespace ndn::net::detail {
 
 ndn::nfd::LinkType
 getLinkType(const std::string& ifName)
@@ -36,8 +34,6 @@
   return nfd::LINK_TYPE_NONE;
 }
 
-} // namespace detail
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net::detail
 
 #endif // NDN_CXX_HAVE_OSX_FRAMEWORKS
diff --git a/ndn-cxx/net/impl/link-type-helper.hpp b/ndn-cxx/net/impl/link-type-helper.hpp
index e5bdc23..08fe96e 100644
--- a/ndn-cxx/net/impl/link-type-helper.hpp
+++ b/ndn-cxx/net/impl/link-type-helper.hpp
@@ -26,9 +26,7 @@
 
 #include <string>
 
-namespace ndn {
-namespace net {
-namespace detail {
+namespace ndn::net::detail {
 
 /**
  * @brief Obtain information about WiFi link type
@@ -36,8 +34,6 @@
 ndn::nfd::LinkType
 getLinkType(const std::string& ifName);
 
-} // namespace detail
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net::detail
 
 #endif // NDN_CXX_NET_IMPL_LINK_TYPE_HELPER_HPP
diff --git a/ndn-cxx/net/impl/linux-if-constants.cpp b/ndn-cxx/net/impl/linux-if-constants.cpp
index 68bb9db..913c52c 100644
--- a/ndn-cxx/net/impl/linux-if-constants.cpp
+++ b/ndn-cxx/net/impl/linux-if-constants.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,9 +28,7 @@
 #include <sys/socket.h>
 #include <linux/if.h>
 
-namespace ndn {
-namespace net {
-namespace linux_if {
+namespace ndn::net::linux_if {
 
 const uint32_t FLAG_LOWER_UP = IFF_LOWER_UP;
 const uint32_t FLAG_DORMANT  = IFF_DORMANT;
@@ -44,8 +42,6 @@
 const uint8_t OPER_STATE_DORMANT        = IF_OPER_DORMANT;
 const uint8_t OPER_STATE_UP             = IF_OPER_UP;
 
-} // namespace linux_if
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net::linux_if
 
 #endif // __linux__
diff --git a/ndn-cxx/net/impl/linux-if-constants.hpp b/ndn-cxx/net/impl/linux-if-constants.hpp
index ab8a4cc..9d58dc0 100644
--- a/ndn-cxx/net/impl/linux-if-constants.hpp
+++ b/ndn-cxx/net/impl/linux-if-constants.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,7 @@
 
 #include <cstdint>
 
-namespace ndn {
-namespace net {
-namespace linux_if {
+namespace ndn::net::linux_if {
 
 // linux/if.h and net/if.h cannot be (directly or indirectly) included in the
 // same translation unit because they contain duplicate declarations, therefore
@@ -50,9 +48,7 @@
 extern const uint8_t OPER_STATE_DORMANT;
 extern const uint8_t OPER_STATE_UP;
 
-} // namespace linux_if
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net::linux_if
 
 #endif // __linux__
 #endif // NDN_CXX_NET_LINUX_IF_CONSTANTS_HPP
diff --git a/ndn-cxx/net/impl/netlink-message.hpp b/ndn-cxx/net/impl/netlink-message.hpp
index 5eb44b8..d00b106 100644
--- a/ndn-cxx/net/impl/netlink-message.hpp
+++ b/ndn-cxx/net/impl/netlink-message.hpp
@@ -42,8 +42,7 @@
 
 #include <boost/asio/ip/address.hpp>
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 template<typename T>
 constexpr size_t
@@ -270,7 +269,6 @@
   std::map<uint16_t, const T*> m_attrs;
 };
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETLINK_MESSAGE_HPP
diff --git a/ndn-cxx/net/impl/netlink-socket.cpp b/ndn-cxx/net/impl/netlink-socket.cpp
index b12998c..b3f59f7 100644
--- a/ndn-cxx/net/impl/netlink-socket.cpp
+++ b/ndn-cxx/net/impl/netlink-socket.cpp
@@ -39,10 +39,9 @@
 #define NETLINK_GET_STRICT_CHK 12
 #endif
 
-NDN_LOG_INIT(ndn.NetworkMonitor);
+namespace ndn::net {
 
-namespace ndn {
-namespace net {
+NDN_LOG_INIT(ndn.NetworkMonitor);
 
 // satisfies Asio's SettableSocketOption type requirements
 template<int OptName>
@@ -607,5 +606,4 @@
   return NetlinkSocket::nlmsgTypeToString(type);
 }
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
diff --git a/ndn-cxx/net/impl/netlink-socket.hpp b/ndn-cxx/net/impl/netlink-socket.hpp
index af10173..34a5e9e 100644
--- a/ndn-cxx/net/impl/netlink-socket.hpp
+++ b/ndn-cxx/net/impl/netlink-socket.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -35,8 +35,7 @@
 #error "This file should not be included ..."
 #endif
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 class NetlinkMessage;
 
@@ -110,8 +109,8 @@
 public:
   GenlFamilyResolver(std::string familyName, GenlSocket& socket);
 
-  util::Signal<GenlFamilyResolver, uint16_t> onResolved;
-  util::Signal<GenlFamilyResolver> onError;
+  signal::Signal<GenlFamilyResolver, uint16_t> onResolved;
+  signal::Signal<GenlFamilyResolver> onError;
 
 private:
   void
@@ -153,7 +152,6 @@
   std::map<std::string, GenlFamilyResolver> m_familyResolvers; ///< family name => resolver instance
 };
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETLINK_SOCKET_HPP
diff --git a/ndn-cxx/net/impl/network-monitor-impl-netlink.cpp b/ndn-cxx/net/impl/network-monitor-impl-netlink.cpp
index 0862371..ca1d749 100644
--- a/ndn-cxx/net/impl/network-monitor-impl-netlink.cpp
+++ b/ndn-cxx/net/impl/network-monitor-impl-netlink.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -39,10 +39,9 @@
 #define RTEXT_FILTER_SKIP_STATS (1 << 3)
 #endif
 
-NDN_LOG_INIT(ndn.NetworkMonitor);
+namespace ndn::net {
 
-namespace ndn {
-namespace net {
+NDN_LOG_INIT(ndn.NetworkMonitor);
 
 NetworkMonitorImplNetlink::NetworkMonitorImplNetlink(boost::asio::io_service& io)
   : m_rtnlSocket(io)
@@ -451,5 +450,4 @@
 #endif // NDN_CXX_HAVE_NETLINK_EXT_ACK
 }
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
diff --git a/ndn-cxx/net/impl/network-monitor-impl-netlink.hpp b/ndn-cxx/net/impl/network-monitor-impl-netlink.hpp
index a7c7193..78501ae 100644
--- a/ndn-cxx/net/impl/network-monitor-impl-netlink.hpp
+++ b/ndn-cxx/net/impl/network-monitor-impl-netlink.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -35,8 +35,7 @@
 
 #include <map>
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 class NetworkMonitorImplNetlink : public NetworkMonitorImpl
 {
@@ -104,7 +103,6 @@
   } m_phase = ENUMERATION_NOT_STARTED;
 };
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETWORK_MONITOR_IMPL_NETLINK_HPP
diff --git a/ndn-cxx/net/impl/network-monitor-impl-noop.hpp b/ndn-cxx/net/impl/network-monitor-impl-noop.hpp
index 617f319..d0a0d08 100644
--- a/ndn-cxx/net/impl/network-monitor-impl-noop.hpp
+++ b/ndn-cxx/net/impl/network-monitor-impl-noop.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,8 +26,7 @@
 
 #include "ndn-cxx/net/network-monitor.hpp"
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 class NetworkMonitorImplNoop : public NetworkMonitorImpl
 {
@@ -56,7 +55,6 @@
   }
 };
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETWORK_MONITOR_IMPL_NOOP_HPP
diff --git a/ndn-cxx/net/impl/network-monitor-impl-osx.cpp b/ndn-cxx/net/impl/network-monitor-impl-osx.cpp
index b10c6eb..0b543d7 100644
--- a/ndn-cxx/net/impl/network-monitor-impl-osx.cpp
+++ b/ndn-cxx/net/impl/network-monitor-impl-osx.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -68,12 +68,11 @@
 #include <boost/range/adaptor/map.hpp>
 #include <boost/range/algorithm_ext/push_back.hpp>
 
+namespace ndn::net {
+
 NDN_LOG_INIT(ndn.NetworkMonitor);
 
-namespace ndn {
-namespace net {
-
-using detail::CFReleaser;
+using ndn::detail::CFReleaser;
 
 class IfAddrs : noncopyable
 {
@@ -461,5 +460,4 @@
   }
 }
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
diff --git a/ndn-cxx/net/impl/network-monitor-impl-osx.hpp b/ndn-cxx/net/impl/network-monitor-impl-osx.hpp
index 67a28f8..099ae8b 100644
--- a/ndn-cxx/net/impl/network-monitor-impl-osx.hpp
+++ b/ndn-cxx/net/impl/network-monitor-impl-osx.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -38,8 +38,7 @@
 #include <boost/asio/ip/udp.hpp>
 #include <map>
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 class IfAddrs;
 
@@ -111,7 +110,6 @@
   boost::asio::ip::udp::socket m_ioctlSocket;
 };
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETWORK_MONITOR_IMPL_OSX_HPP
diff --git a/ndn-cxx/net/network-address.cpp b/ndn-cxx/net/network-address.cpp
index f8e8a6e..40ff6fa 100644
--- a/ndn-cxx/net/network-address.cpp
+++ b/ndn-cxx/net/network-address.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include <linux/if_addr.h>
 #endif
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 std::ostream&
 operator<<(std::ostream& os, AddressScope scope)
@@ -79,5 +78,4 @@
   return os << addr.getIp() << '/' << static_cast<unsigned int>(addr.getPrefixLength());
 }
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
diff --git a/ndn-cxx/net/network-address.hpp b/ndn-cxx/net/network-address.hpp
index 1bb435c..d70e611 100644
--- a/ndn-cxx/net/network-address.hpp
+++ b/ndn-cxx/net/network-address.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 
 #include <boost/asio/ip/address.hpp>
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 enum class AddressFamily {
   UNSPECIFIED,
@@ -140,7 +139,6 @@
 std::ostream&
 operator<<(std::ostream& os, const NetworkAddress& address);
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETWORK_ADDRESS_HPP
diff --git a/ndn-cxx/net/network-interface.cpp b/ndn-cxx/net/network-interface.cpp
index 2adf2ef..250e1d6 100644
--- a/ndn-cxx/net/network-interface.cpp
+++ b/ndn-cxx/net/network-interface.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,10 +28,9 @@
 
 #include <net/if.h>
 
-NDN_LOG_INIT(ndn.NetworkMonitor);
+namespace ndn::net {
 
-namespace ndn {
-namespace net {
+NDN_LOG_INIT(ndn.NetworkMonitor);
 
 NetworkInterface::NetworkInterface()
   : m_index(0)
@@ -241,5 +240,4 @@
   return os;
 }
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
diff --git a/ndn-cxx/net/network-interface.hpp b/ndn-cxx/net/network-interface.hpp
index 29277c9..dca92b9 100644
--- a/ndn-cxx/net/network-interface.hpp
+++ b/ndn-cxx/net/network-interface.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,12 +26,11 @@
 
 #include "ndn-cxx/net/ethernet.hpp"
 #include "ndn-cxx/net/network-address.hpp"
-#include "ndn-cxx/util/signal.hpp"
+#include "ndn-cxx/util/signal/signal.hpp"
 
 #include <set>
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 /** @brief Indicates the hardware type of a network interface
  */
@@ -71,19 +70,19 @@
 public: // signals, marked 'mutable' so they can be connected on 'const NetworkInterface'
   /** @brief Fires when interface state changes
    */
-  mutable util::Signal<NetworkInterface, InterfaceState /*old*/, InterfaceState /*new*/> onStateChanged;
+  mutable signal::Signal<NetworkInterface, InterfaceState /*old*/, InterfaceState /*new*/> onStateChanged;
 
   /** @brief Fires when interface mtu changes
    */
-  mutable util::Signal<NetworkInterface, uint32_t /*old*/, uint32_t /*new*/> onMtuChanged;
+  mutable signal::Signal<NetworkInterface, uint32_t /*old*/, uint32_t /*new*/> onMtuChanged;
 
   /** @brief Fires when a network-layer address is added to the interface
    */
-  mutable util::Signal<NetworkInterface, NetworkAddress> onAddressAdded;
+  mutable signal::Signal<NetworkInterface, NetworkAddress> onAddressAdded;
 
   /** @brief Fires when a network-layer address is removed from the interface
    */
-  mutable util::Signal<NetworkInterface, NetworkAddress> onAddressRemoved;
+  mutable signal::Signal<NetworkInterface, NetworkAddress> onAddressRemoved;
 
 public: // getters
   /** @brief Returns an opaque ID that uniquely identifies the interface on the system
@@ -249,7 +248,6 @@
 std::ostream&
 operator<<(std::ostream& os, const NetworkInterface& interface);
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETWORK_INTERFACE_HPP
diff --git a/ndn-cxx/net/network-monitor-stub.cpp b/ndn-cxx/net/network-monitor-stub.cpp
index c84d8ae..bb8e49e 100644
--- a/ndn-cxx/net/network-monitor-stub.cpp
+++ b/ndn-cxx/net/network-monitor-stub.cpp
@@ -29,8 +29,7 @@
 #include <boost/range/adaptor/map.hpp>
 #include <boost/range/algorithm/copy.hpp>
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 class NetworkMonitorImplStub : public NetworkMonitorImpl
 {
@@ -134,5 +133,4 @@
   this->getImpl().emitEnumerationCompleted();
 }
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
diff --git a/ndn-cxx/net/network-monitor-stub.hpp b/ndn-cxx/net/network-monitor-stub.hpp
index 25f8849..b6bf852 100644
--- a/ndn-cxx/net/network-monitor-stub.hpp
+++ b/ndn-cxx/net/network-monitor-stub.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/net/network-monitor.hpp"
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 class NetworkMonitorImplStub;
 
@@ -85,7 +84,6 @@
   getImpl();
 };
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETWORK_MONITOR_STUB_HPP
diff --git a/ndn-cxx/net/network-monitor.cpp b/ndn-cxx/net/network-monitor.cpp
index 511d750..79e601f 100644
--- a/ndn-cxx/net/network-monitor.cpp
+++ b/ndn-cxx/net/network-monitor.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -37,10 +37,9 @@
 #define NETWORK_MONITOR_IMPL_TYPE NetworkMonitorImplNoop
 #endif
 
-NDN_LOG_INIT(ndn.NetworkMonitor);
+namespace ndn::net {
 
-namespace ndn {
-namespace net {
+NDN_LOG_INIT(ndn.NetworkMonitor);
 
 static unique_ptr<NetworkMonitorImpl>
 makeNetworkMonitorImpl(boost::asio::io_service& io)
@@ -94,5 +93,4 @@
   return shared_ptr<NetworkInterface>(new NetworkInterface);
 }
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
diff --git a/ndn-cxx/net/network-monitor.hpp b/ndn-cxx/net/network-monitor.hpp
index 3bd8927..f45c4d5 100644
--- a/ndn-cxx/net/network-monitor.hpp
+++ b/ndn-cxx/net/network-monitor.hpp
@@ -27,11 +27,12 @@
 
 #include "ndn-cxx/detail/asio-fwd.hpp"
 #include "ndn-cxx/net/network-interface.hpp"
+#include "ndn-cxx/util/signal/emit.hpp"
+#include "ndn-cxx/util/signal/signal.hpp"
 
 #include <vector>
 
-namespace ndn {
-namespace net {
+namespace ndn::net {
 
 class NetworkMonitorImpl;
 
@@ -112,20 +113,20 @@
 
 public: // signals
   /// Fires when the enumeration of all network interfaces on the system is complete.
-  util::Signal<NetworkMonitorImpl>& onEnumerationCompleted;
+  signal::Signal<NetworkMonitorImpl>& onEnumerationCompleted;
 
   /// Fires whenever a new interface is detected on the system.
-  util::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>>& onInterfaceAdded;
+  signal::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>>& onInterfaceAdded;
 
   /**
    * @brief Fires whenever an interface disappears from the system.
    * @note The NetworkInterface object has already been removed from the list
    *       returned by listNetworkInterfaces() when this signal is emitted.
    */
-  util::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>>& onInterfaceRemoved;
+  signal::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>>& onInterfaceRemoved;
 
   /// @deprecated Only for backward compatibility
-  util::Signal<NetworkMonitorImpl>& onNetworkStateChanged;
+  signal::Signal<NetworkMonitorImpl>& onNetworkStateChanged;
 };
 
 class NetworkMonitorImpl : noncopyable
@@ -150,10 +151,10 @@
   makeNetworkInterface();
 
 public:
-  util::Signal<NetworkMonitorImpl> onEnumerationCompleted;
-  util::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>> onInterfaceAdded;
-  util::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>> onInterfaceRemoved;
-  util::Signal<NetworkMonitorImpl> onNetworkStateChanged;
+  signal::Signal<NetworkMonitorImpl> onEnumerationCompleted;
+  signal::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>> onInterfaceAdded;
+  signal::Signal<NetworkMonitorImpl, shared_ptr<const NetworkInterface>> onInterfaceRemoved;
+  signal::Signal<NetworkMonitorImpl> onNetworkStateChanged;
 
 protected:
   DECLARE_SIGNAL_EMIT(onEnumerationCompleted)
@@ -162,7 +163,6 @@
   DECLARE_SIGNAL_EMIT(onNetworkStateChanged)
 };
 
-} // namespace net
-} // namespace ndn
+} // namespace ndn::net
 
 #endif // NDN_CXX_NET_NETWORK_MONITOR_HPP
diff --git a/ndn-cxx/security/additional-description.cpp b/ndn-cxx/security/additional-description.cpp
index 727cb57..52c4650 100644
--- a/ndn-cxx/security/additional-description.cpp
+++ b/ndn-cxx/security/additional-description.cpp
@@ -23,9 +23,7 @@
 #include "ndn-cxx/encoding/block-helpers.hpp"
 #include "ndn-cxx/util/ostream-joiner.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 constexpr size_t KEY_OFFSET = 0;
 constexpr size_t VALUE_OFFSET = 1;
@@ -168,6 +166,4 @@
   return os << "]";
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/additional-description.hpp b/ndn-cxx/security/additional-description.hpp
index d42aca7..09fa9c6 100644
--- a/ndn-cxx/security/additional-description.hpp
+++ b/ndn-cxx/security/additional-description.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,7 @@
 
 #include <map>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Represents an %AdditionalDescription TLV element.
@@ -136,9 +134,6 @@
 std::ostream&
 operator<<(std::ostream& os, const AdditionalDescription& desc);
 
-} // inline namespace v2
-
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_ADDITIONAL_DESCRIPTION_HPP
diff --git a/ndn-cxx/security/certificate-bundle-fetcher.cpp b/ndn-cxx/security/certificate-bundle-fetcher.cpp
index f360220..1179bf0 100644
--- a/ndn-cxx/security/certificate-bundle-fetcher.cpp
+++ b/ndn-cxx/security/certificate-bundle-fetcher.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,7 @@
 #include "ndn-cxx/security/validation-state.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 NDN_LOG_INIT(ndn.security.CertificateBundleFetcher);
 
@@ -230,6 +228,4 @@
   return bundleName;
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate-bundle-fetcher.hpp b/ndn-cxx/security/certificate-bundle-fetcher.hpp
index 6e9d683..1d3e4ff 100644
--- a/ndn-cxx/security/certificate-bundle-fetcher.hpp
+++ b/ndn-cxx/security/certificate-bundle-fetcher.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 #include "ndn-cxx/tag.hpp"
 #include "ndn-cxx/security/certificate-fetcher-from-network.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Fetch certificate bundle from the network
@@ -144,8 +142,6 @@
   time::milliseconds m_bundleInterestLifetime;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_BUNDLE_FETCHER_HPP
diff --git a/ndn-cxx/security/certificate-cache.cpp b/ndn-cxx/security/certificate-cache.cpp
index bf5cb6c..4321737 100644
--- a/ndn-cxx/security/certificate-cache.cpp
+++ b/ndn-cxx/security/certificate-cache.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,18 +22,10 @@
 #include "ndn-cxx/security/certificate-cache.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 NDN_LOG_INIT(ndn.security.CertificateCache);
 
-time::nanoseconds
-CertificateCache::getDefaultLifetime()
-{
-  return 1_h;
-}
-
 CertificateCache::CertificateCache(const time::nanoseconds& maxLifetime)
   : m_certsByTime(m_certs.get<0>())
   , m_certsByName(m_certs.get<1>())
@@ -44,14 +36,14 @@
 void
 CertificateCache::insert(const Certificate& cert)
 {
-  time::system_clock::TimePoint notAfterTime = cert.getValidityPeriod().getPeriod().second;
-  time::system_clock::TimePoint now = time::system_clock::now();
+  auto notAfterTime = cert.getValidityPeriod().getPeriod().second;
+  auto now = time::system_clock::now();
   if (notAfterTime < now) {
     NDN_LOG_DEBUG("Not adding " << cert.getName() << ": already expired at " << time::toIsoString(notAfterTime));
     return;
   }
 
-  time::system_clock::TimePoint removalTime = std::min(notAfterTime, now + m_maxLifetime);
+  auto removalTime = std::min(notAfterTime, now + m_maxLifetime);
   NDN_LOG_DEBUG("Adding " << cert.getName() << ", will remove in "
                 << time::duration_cast<time::seconds>(removalTime - now));
   m_certs.insert(Entry(cert, removalTime));
@@ -98,7 +90,7 @@
 void
 CertificateCache::refresh()
 {
-  time::system_clock::TimePoint now = time::system_clock::now();
+  auto now = time::system_clock::now();
 
   auto cIt = m_certsByTime.begin();
   while (cIt != m_certsByTime.end() && cIt->removalTime < now) {
@@ -107,6 +99,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate-cache.hpp b/ndn-cxx/security/certificate-cache.hpp
index 13e8d33..f86ca59 100644
--- a/ndn-cxx/security/certificate-cache.hpp
+++ b/ndn-cxx/security/certificate-cache.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,9 +30,7 @@
 #include <boost/multi_index/mem_fun.hpp>
 #include <boost/multi_index/member.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Represents a container for verified certificates.
@@ -92,7 +90,8 @@
   class Entry
   {
   public:
-    Entry(const Certificate& cert, const time::system_clock::TimePoint& removalTime)
+    explicit
+    Entry(const Certificate& cert, const time::system_clock::time_point& removalTime)
       : cert(cert)
       , removalTime(removalTime)
     {
@@ -106,7 +105,7 @@
 
   public:
     Certificate cert;
-    time::system_clock::TimePoint removalTime;
+    time::system_clock::time_point removalTime;
   };
 
   /**
@@ -116,33 +115,34 @@
   refresh();
 
 public:
-  static time::nanoseconds
-  getDefaultLifetime();
+  static constexpr time::nanoseconds
+  getDefaultLifetime() noexcept
+  {
+    return 1_h;
+  }
 
 private:
-  /// @todo Switch to InMemoryStorateTimeout after it is available (task #3917)
-  typedef boost::multi_index::multi_index_container<
+  /// @todo Switch to InMemoryStorageTimeout after it is available (task #3917)
+  using CertIndex = boost::multi_index::multi_index_container<
     Entry,
     boost::multi_index::indexed_by<
       boost::multi_index::ordered_non_unique<
-        boost::multi_index::member<Entry, const time::system_clock::TimePoint, &Entry::removalTime>
+        boost::multi_index::member<Entry, const time::system_clock::time_point, &Entry::removalTime>
       >,
       boost::multi_index::ordered_unique<
         boost::multi_index::const_mem_fun<Entry, const Name&, &Entry::getCertName>
       >
     >
-  > CertIndex;
+  >;
+  using CertIndexByTime = CertIndex::nth_index<0>::type;
+  using CertIndexByName = CertIndex::nth_index<1>::type;
 
-  typedef CertIndex::nth_index<0>::type CertIndexByTime;
-  typedef CertIndex::nth_index<1>::type CertIndexByName;
   CertIndex m_certs;
   CertIndexByTime& m_certsByTime;
   CertIndexByName& m_certsByName;
   time::nanoseconds m_maxLifetime;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_CACHE_HPP
diff --git a/ndn-cxx/security/certificate-fetcher-direct-fetch.cpp b/ndn-cxx/security/certificate-fetcher-direct-fetch.cpp
index 06c6a57..c7df4f2 100644
--- a/ndn-cxx/security/certificate-fetcher-direct-fetch.cpp
+++ b/ndn-cxx/security/certificate-fetcher-direct-fetch.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 #include "ndn-cxx/security/certificate-request.hpp"
 #include "ndn-cxx/security/validation-state.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 CertificateFetcherDirectFetch::CertificateFetcherDirectFetch(Face& face)
   : CertificateFetcherFromNetwork(face)
@@ -94,6 +92,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate-fetcher-direct-fetch.hpp b/ndn-cxx/security/certificate-fetcher-direct-fetch.hpp
index 0ec8bb5..f11a662 100644
--- a/ndn-cxx/security/certificate-fetcher-direct-fetch.hpp
+++ b/ndn-cxx/security/certificate-fetcher-direct-fetch.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/certificate-fetcher-from-network.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Extends CertificateFetcherFromNetwork to fetch certificates from the incoming face of
@@ -58,8 +56,6 @@
   bool m_wantDirectInterestOnly = false;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_FETCHER_DIRECT_FETCH_HPP
diff --git a/ndn-cxx/security/certificate-fetcher-from-network.cpp b/ndn-cxx/security/certificate-fetcher-from-network.cpp
index 65c70c9..0861c0d 100644
--- a/ndn-cxx/security/certificate-fetcher-from-network.cpp
+++ b/ndn-cxx/security/certificate-fetcher-from-network.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 #include "ndn-cxx/security/validation-state.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 NDN_LOG_INIT(ndn.security.CertificateFetcher);
 
@@ -114,6 +112,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate-fetcher-from-network.hpp b/ndn-cxx/security/certificate-fetcher-from-network.hpp
index 6074c66..fedd880 100644
--- a/ndn-cxx/security/certificate-fetcher-from-network.hpp
+++ b/ndn-cxx/security/certificate-fetcher-from-network.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -35,7 +35,6 @@
 } // namespace lp
 
 namespace security {
-inline namespace v2 {
 
 /**
  * @brief Fetch missing keys from the network
@@ -83,7 +82,6 @@
   Scheduler m_scheduler;
 };
 
-} // inline namespace v2
 } // namespace security
 } // namespace ndn
 
diff --git a/ndn-cxx/security/certificate-fetcher-offline.cpp b/ndn-cxx/security/certificate-fetcher-offline.cpp
index a613a9e..00709b4 100644
--- a/ndn-cxx/security/certificate-fetcher-offline.cpp
+++ b/ndn-cxx/security/certificate-fetcher-offline.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,7 @@
 #include "ndn-cxx/security/certificate-request.hpp"
 #include "ndn-cxx/security/validation-state.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 void
 CertificateFetcherOffline::doFetch(const shared_ptr<CertificateRequest>& certRequest,
@@ -36,6 +34,4 @@
                "Cannot fetch `" + certRequest->interest.getName().toUri() + "` in offline mode"});
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate-fetcher-offline.hpp b/ndn-cxx/security/certificate-fetcher-offline.hpp
index 84412eb..55c9a86 100644
--- a/ndn-cxx/security/certificate-fetcher-offline.hpp
+++ b/ndn-cxx/security/certificate-fetcher-offline.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/certificate-fetcher.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Certificate fetcher realization that does not fetch keys (always offline)
@@ -39,8 +37,6 @@
           const ValidationContinuation& continueValidation) override;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_FETCHER_OFFLINE_HPP
diff --git a/ndn-cxx/security/certificate-fetcher.cpp b/ndn-cxx/security/certificate-fetcher.cpp
index 931b83e..408c61d 100644
--- a/ndn-cxx/security/certificate-fetcher.cpp
+++ b/ndn-cxx/security/certificate-fetcher.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/validation-state.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 NDN_LOG_INIT(ndn.security.CertificateFetcher);
 
@@ -66,6 +64,4 @@
           });
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate-fetcher.hpp b/ndn-cxx/security/certificate-fetcher.hpp
index fa4b9eb..541342e 100644
--- a/ndn-cxx/security/certificate-fetcher.hpp
+++ b/ndn-cxx/security/certificate-fetcher.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/detail/common.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 class Certificate;
 class CertificateRequest;
@@ -84,8 +82,6 @@
   CertificateStorage* m_certStorage;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_FETCHER_HPP
diff --git a/ndn-cxx/security/certificate-request.hpp b/ndn-cxx/security/certificate-request.hpp
index bb270dd..2aa9201 100644
--- a/ndn-cxx/security/certificate-request.hpp
+++ b/ndn-cxx/security/certificate-request.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/interest.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Request for a certificate, associated with the number of attempts.
@@ -58,8 +56,6 @@
   time::milliseconds waitAfterNack = 500_ms;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_REQUEST_HPP
diff --git a/ndn-cxx/security/certificate-storage.cpp b/ndn-cxx/security/certificate-storage.cpp
index 95a2cb4..9e9a37c 100644
--- a/ndn-cxx/security/certificate-storage.cpp
+++ b/ndn-cxx/security/certificate-storage.cpp
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/certificate-storage.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 CertificateStorage::CertificateStorage()
   : m_verifiedCertCache(1_h)
@@ -103,6 +101,4 @@
   return m_unverifiedCertCache;
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate-storage.hpp b/ndn-cxx/security/certificate-storage.hpp
index 0f5a126..dbb72e0 100644
--- a/ndn-cxx/security/certificate-storage.hpp
+++ b/ndn-cxx/security/certificate-storage.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 #include "ndn-cxx/security/certificate-cache.hpp"
 #include "ndn-cxx/security/trust-anchor-container.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Storage for trusted anchors, verified certificate cache, and unverified certificate cache.
@@ -135,8 +133,6 @@
   CertificateCache m_unverifiedCertCache;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_STORAGE_HPP
diff --git a/ndn-cxx/security/certificate.cpp b/ndn-cxx/security/certificate.cpp
index 67706fd..ac74913 100644
--- a/ndn-cxx/security/certificate.cpp
+++ b/ndn-cxx/security/certificate.cpp
@@ -27,9 +27,7 @@
 #include "ndn-cxx/security/transform.hpp"
 #include "ndn-cxx/util/indented-stream.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 Certificate::Certificate()
 {
@@ -92,7 +90,7 @@
 }
 
 bool
-Certificate::isValid(const time::system_clock::TimePoint& ts) const
+Certificate::isValid(const time::system_clock::time_point& ts) const
 {
   return getSignatureInfo().getValidityPeriod().isValid(ts);
 }
@@ -204,6 +202,4 @@
   return certName.getPrefix(Certificate::KEY_ID_OFFSET + 1); // trim everything after key id
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/certificate.hpp b/ndn-cxx/security/certificate.hpp
index b533494..8061361 100644
--- a/ndn-cxx/security/certificate.hpp
+++ b/ndn-cxx/security/certificate.hpp
@@ -27,9 +27,7 @@
 
 #include "ndn-cxx/data.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Represents an NDN certificate.
@@ -132,7 +130,7 @@
    * @brief Check if the certificate is valid at @p ts.
    */
   bool
-  isValid(const time::system_clock::TimePoint& ts = time::system_clock::now()) const;
+  isValid(const time::system_clock::time_point& ts = time::system_clock::now()) const;
 
   /**
    * @brief Get extension with TLV @p type
@@ -176,8 +174,6 @@
 Name
 extractKeyNameFromCertName(const Name& certName);
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_CERTIFICATE_HPP
diff --git a/ndn-cxx/security/detail/certificate-bundle-decoder.cpp b/ndn-cxx/security/detail/certificate-bundle-decoder.cpp
index c66a50b..362da2e 100644
--- a/ndn-cxx/security/detail/certificate-bundle-decoder.cpp
+++ b/ndn-cxx/security/detail/certificate-bundle-decoder.cpp
@@ -22,9 +22,7 @@
 #include "ndn-cxx/security/detail/certificate-bundle-decoder.hpp"
 #include "ndn-cxx/util/scope.hpp"
 
-namespace ndn {
-namespace security {
-namespace detail {
+namespace ndn::security::detail {
 
 void
 CertificateBundleDecoder::append(const Block& segment)
@@ -60,6 +58,4 @@
   }
 }
 
-} // namespace detail
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::detail
diff --git a/ndn-cxx/security/detail/certificate-bundle-decoder.hpp b/ndn-cxx/security/detail/certificate-bundle-decoder.hpp
index 17f88ca..61ed825 100644
--- a/ndn-cxx/security/detail/certificate-bundle-decoder.hpp
+++ b/ndn-cxx/security/detail/certificate-bundle-decoder.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,13 +23,12 @@
 #define NDN_CXX_SECURITY_DETAIL_CERTIFICATE_BUNDLE_DECODER_HPP
 
 #include "ndn-cxx/security/certificate.hpp"
-#include "ndn-cxx/util/signal.hpp"
+#include "ndn-cxx/util/signal/signal.hpp"
 
-namespace ndn {
-namespace security {
-namespace detail {
+namespace ndn::security::detail {
 
-/** @brief Helper class to decode a certificate bundle.
+/**
+ * @brief Helper class to decode a certificate bundle.
  */
 class CertificateBundleDecoder
 {
@@ -58,7 +57,7 @@
   /**
    * @brief Emitted every time a certificate is successfully decoded.
    */
-  util::Signal<CertificateBundleDecoder, Certificate> onCertDecoded;
+  signal::Signal<CertificateBundleDecoder, Certificate> onCertDecoded;
 
 private:
   void
@@ -69,8 +68,6 @@
   bool m_hasError = false;
 };
 
-} // namespace detail
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::detail
 
 #endif // NDN_CXX_SECURITY_DETAIL_CERTIFICATE_BUNDLE_DECODER_HPP
diff --git a/ndn-cxx/security/impl/openssl-helper.cpp b/ndn-cxx/security/impl/openssl-helper.cpp
index 0b14fa1..5abf6be 100644
--- a/ndn-cxx/security/impl/openssl-helper.cpp
+++ b/ndn-cxx/security/impl/openssl-helper.cpp
@@ -23,9 +23,7 @@
 
 #include <limits>
 
-namespace ndn {
-namespace security {
-namespace detail {
+namespace ndn::security::detail {
 
 const EVP_MD*
 digestAlgorithmToEvpMd(DigestAlgorithm algo)
@@ -123,6 +121,4 @@
   return n >= 0 && static_cast<size_t>(n) == buf.size();
 }
 
-} // namespace detail
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::detail
diff --git a/ndn-cxx/security/impl/openssl-helper.hpp b/ndn-cxx/security/impl/openssl-helper.hpp
index e348391..2863277 100644
--- a/ndn-cxx/security/impl/openssl-helper.hpp
+++ b/ndn-cxx/security/impl/openssl-helper.hpp
@@ -27,9 +27,7 @@
 #include <openssl/bio.h>
 #include <openssl/evp.h>
 
-namespace ndn {
-namespace security {
-namespace detail {
+namespace ndn::security::detail {
 
 [[nodiscard]] const EVP_MD*
 digestAlgorithmToEvpMd(DigestAlgorithm algo);
@@ -96,8 +94,6 @@
   BIO* m_bio;
 };
 
-} // namespace detail
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::detail
 
 #endif // NDN_CXX_SECURITY_IMPL_OPENSSL_HELPER_HPP
diff --git a/ndn-cxx/security/interest-signer.cpp b/ndn-cxx/security/interest-signer.cpp
index 5b12c83..ae6fe9d 100644
--- a/ndn-cxx/security/interest-signer.cpp
+++ b/ndn-cxx/security/interest-signer.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,8 +22,7 @@
 #include "ndn-cxx/security/interest-signer.hpp"
 #include "ndn-cxx/util/random.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 InterestSigner::InterestSigner(KeyChain& keyChain)
   : m_keyChain(keyChain)
@@ -73,7 +72,7 @@
   return interest;
 }
 
-time::system_clock::TimePoint
+time::system_clock::time_point
 InterestSigner::getFreshTimestamp()
 {
   auto timestamp = time::system_clock::now();
@@ -87,5 +86,4 @@
   return timestamp;
 }
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/interest-signer.hpp b/ndn-cxx/security/interest-signer.hpp
index 76d73f5..e47e704 100644
--- a/ndn-cxx/security/interest-signer.hpp
+++ b/ndn-cxx/security/interest-signer.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/security/key-chain.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 /**
  * @brief Helper class to create signed Interests
@@ -78,16 +77,15 @@
   /**
    * @brief Get current timestamp, but ensure it is unique by increasing by 1 ms if already used
    */
-  time::system_clock::TimePoint
+  time::system_clock::time_point
   getFreshTimestamp();
 
 private:
   KeyChain& m_keyChain;
-  time::system_clock::TimePoint m_lastUsedTimestamp;
+  time::system_clock::time_point m_lastUsedTimestamp;
   uint64_t m_lastUsedSeqNum;
 };
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_INTEREST_SIGNER_HPP
diff --git a/ndn-cxx/security/key-chain.cpp b/ndn-cxx/security/key-chain.cpp
index 2e27086..16f6c42 100644
--- a/ndn-cxx/security/key-chain.cpp
+++ b/ndn-cxx/security/key-chain.cpp
@@ -46,8 +46,9 @@
 #include <boost/lexical_cast.hpp>
 #include <cstdlib>  // for std::getenv()
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
+
+NDN_LOG_INIT(ndn.security.KeyChain);
 
 // When static library is used, not everything is compiled into the resulting binary.
 // Therefore, the following standard PIB and TPMs need to be registered here.
@@ -66,10 +67,6 @@
 NDN_CXX_KEYCHAIN_REGISTER_TPM_BACKEND(BackEndMem);
 } // namespace tpm
 
-inline namespace v2 {
-
-NDN_LOG_INIT(ndn.security.KeyChain);
-
 const name::Component SELF{"self"};
 
 KeyChain::PibFactories&
@@ -782,6 +779,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/key-chain.hpp b/ndn-cxx/security/key-chain.hpp
index 4257cae..93787be 100644
--- a/ndn-cxx/security/key-chain.hpp
+++ b/ndn-cxx/security/key-chain.hpp
@@ -30,8 +30,10 @@
 #include "ndn-cxx/security/signing-info.hpp"
 #include "ndn-cxx/security/tpm/tpm.hpp"
 
-namespace ndn {
-namespace security {
+/**
+ * @brief Contains the ndn-cxx security framework.
+ */
+namespace ndn::security {
 
 /**
  * @brief Options to KeyChain::makeCertificate().
@@ -73,8 +75,6 @@
   std::optional<ValidityPeriod> validity;
 };
 
-inline namespace v2 {
-
 /**
  * @brief The main interface for signing key management.
  *
@@ -515,6 +515,12 @@
   static Locator s_defaultTpmLocator;
 };
 
+} // namespace ndn::security
+
+namespace ndn {
+using security::KeyChain;
+} // namespace ndn
+
 /**
  * @brief Register Pib backend class in KeyChain
  *
@@ -547,11 +553,4 @@
   }                                                           \
 } ndnCxxAuto ## TpmType ## TpmRegistrationVariable
 
-} // inline namespace v2
-} // namespace security
-
-using security::KeyChain;
-
-} // namespace ndn
-
 #endif // NDN_CXX_SECURITY_KEY_CHAIN_HPP
diff --git a/ndn-cxx/security/pib/certificate-container.cpp b/ndn-cxx/security/pib/certificate-container.cpp
index 24f66ce..873e37d 100644
--- a/ndn-cxx/security/pib/certificate-container.cpp
+++ b/ndn-cxx/security/pib/certificate-container.cpp
@@ -23,9 +23,7 @@
 #include "ndn-cxx/security/pib/pib-impl.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 NDN_LOG_INIT(ndn.security.CertificateContainer);
 
@@ -124,6 +122,4 @@
   return m_certNames == m_pib->getCertificatesOfKey(m_keyName);
 }
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/certificate-container.hpp b/ndn-cxx/security/pib/certificate-container.hpp
index 52b4520..7c98468 100644
--- a/ndn-cxx/security/pib/certificate-container.hpp
+++ b/ndn-cxx/security/pib/certificate-container.hpp
@@ -28,16 +28,10 @@
 #include <set>
 #include <unordered_map>
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 class PibImpl;
 
-namespace detail {
-class KeyImpl;
-} // namespace detail
-
 /**
  * @brief Container of certificates of a key.
  *
@@ -181,11 +175,9 @@
   const Name m_keyName;
   const shared_ptr<PibImpl> m_pib;
 
-  friend detail::KeyImpl;
+  friend class KeyImpl;
 };
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITY_PIB_CERTIFICATE_CONTAINER_HPP
diff --git a/ndn-cxx/security/pib/identity-container.cpp b/ndn-cxx/security/pib/identity-container.cpp
index 6afeae0..8d80b95 100644
--- a/ndn-cxx/security/pib/identity-container.cpp
+++ b/ndn-cxx/security/pib/identity-container.cpp
@@ -24,9 +24,7 @@
 #include "ndn-cxx/security/pib/pib-impl.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 NDN_LOG_INIT(ndn.security.IdentityContainer);
 
@@ -79,7 +77,7 @@
   NDN_LOG_DEBUG("Adding " << identityName);
   m_pib->addIdentity(identityName);
   auto ret = m_identities.emplace(identityName,
-                                  std::make_shared<detail::IdentityImpl>(identityName, m_pib));
+                                  std::make_shared<IdentityImpl>(identityName, m_pib));
   // consistency check
   BOOST_ASSERT(ret.second);
 
@@ -112,7 +110,7 @@
     NDN_THROW(Pib::Error("Identity `" + identityName.toUri() + "` does not exist"));
   }
 
-  auto id = std::make_shared<detail::IdentityImpl>(identityName, m_pib);
+  auto id = std::make_shared<IdentityImpl>(identityName, m_pib);
   m_identities[identityName] = id;
   return Identity(id);
 }
@@ -131,6 +129,4 @@
   return m_identityNames == m_pib->getIdentities();
 }
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/identity-container.hpp b/ndn-cxx/security/pib/identity-container.hpp
index 75fe3f4..786c7ba 100644
--- a/ndn-cxx/security/pib/identity-container.hpp
+++ b/ndn-cxx/security/pib/identity-container.hpp
@@ -28,17 +28,10 @@
 #include <set>
 #include <unordered_map>
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
-class Pib;
 class PibImpl;
 
-namespace detail {
-class IdentityImpl;
-} // namespace detail
-
 /**
  * @brief Container of identities of a PIB.
  *
@@ -181,17 +174,15 @@
 
 NDN_CXX_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   // cache of loaded IdentityImpl
-  mutable std::unordered_map<Name, shared_ptr<detail::IdentityImpl>> m_identities;
+  mutable std::unordered_map<Name, shared_ptr<IdentityImpl>> m_identities;
 
 private:
   NameSet m_identityNames;
   const shared_ptr<PibImpl> m_pib;
 
-  friend Pib;
+  friend class Pib;
 };
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITY_PIB_IDENTITY_CONTAINER_HPP
diff --git a/ndn-cxx/security/pib/identity.cpp b/ndn-cxx/security/pib/identity.cpp
index 41e103b..c141aa7 100644
--- a/ndn-cxx/security/pib/identity.cpp
+++ b/ndn-cxx/security/pib/identity.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,13 +22,11 @@
 #include "ndn-cxx/security/pib/identity.hpp"
 #include "ndn-cxx/security/pib/impl/identity-impl.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 Identity::Identity() noexcept = default;
 
-Identity::Identity(weak_ptr<detail::IdentityImpl> impl) noexcept
+Identity::Identity(weak_ptr<IdentityImpl> impl) noexcept
   : m_impl(std::move(impl))
 {
 }
@@ -86,7 +84,7 @@
   return !m_impl.expired();
 }
 
-shared_ptr<detail::IdentityImpl>
+shared_ptr<IdentityImpl>
 Identity::lock() const
 {
   auto impl = m_impl.lock();
@@ -103,6 +101,4 @@
          !other.m_impl.owner_before(this->m_impl);
 }
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/identity.hpp b/ndn-cxx/security/pib/identity.hpp
index 31acd9b..b39335b 100644
--- a/ndn-cxx/security/pib/identity.hpp
+++ b/ndn-cxx/security/pib/identity.hpp
@@ -24,20 +24,14 @@
 
 #include "ndn-cxx/security/pib/key-container.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
-inline namespace v2 {
 class KeyChain;
-} // inline namespace v2
 
 namespace pib {
 
 class IdentityContainer;
-
-namespace detail {
 class IdentityImpl;
-} // namespace detail
 
 /**
  * @brief Frontend handle for an identity in the PIB.
@@ -143,7 +137,7 @@
 
 NDN_CXX_PUBLIC_WITH_TESTS_ELSE_PRIVATE: // private interface for IdentityContainer
   explicit
-  Identity(weak_ptr<detail::IdentityImpl> impl) noexcept;
+  Identity(weak_ptr<IdentityImpl> impl) noexcept;
 
 private:
   /**
@@ -151,7 +145,7 @@
    * @return a shared_ptr when the instance is valid
    * @throw std::domain_error the instance is invalid
    */
-  shared_ptr<detail::IdentityImpl>
+  shared_ptr<IdentityImpl>
   lock() const;
 
   bool
@@ -183,7 +177,7 @@
   }
 
 private:
-  weak_ptr<detail::IdentityImpl> m_impl;
+  weak_ptr<IdentityImpl> m_impl;
 
   friend KeyChain;
   friend IdentityContainer;
@@ -193,7 +187,6 @@
 
 using pib::Identity;
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_PIB_IDENTITY_HPP
diff --git a/ndn-cxx/security/pib/impl/identity-impl.cpp b/ndn-cxx/security/pib/impl/identity-impl.cpp
index 0256c54..8c19088 100644
--- a/ndn-cxx/security/pib/impl/identity-impl.cpp
+++ b/ndn-cxx/security/pib/impl/identity-impl.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,7 @@
 #include "ndn-cxx/security/pib/pib-impl.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace detail {
+namespace ndn::security::pib {
 
 NDN_LOG_INIT(ndn.security.Identity);
 
@@ -86,7 +83,4 @@
   return m_defaultKey;
 }
 
-} // namespace detail
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/impl/identity-impl.hpp b/ndn-cxx/security/pib/impl/identity-impl.hpp
index 36f7a3f..553dbad 100644
--- a/ndn-cxx/security/pib/impl/identity-impl.hpp
+++ b/ndn-cxx/security/pib/impl/identity-impl.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,14 +24,10 @@
 
 #include "ndn-cxx/security/pib/key-container.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 class PibImpl;
 
-namespace detail {
-
 /**
  * @brief Backend instance of Identity.
  *
@@ -109,9 +105,6 @@
   mutable Key m_defaultKey;
 };
 
-} // namespace detail
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITY_PIB_IMPL_IDENTITY_IMPL_HPP
diff --git a/ndn-cxx/security/pib/impl/key-impl.cpp b/ndn-cxx/security/pib/impl/key-impl.cpp
index 23b6303..85fc322 100644
--- a/ndn-cxx/security/pib/impl/key-impl.cpp
+++ b/ndn-cxx/security/pib/impl/key-impl.cpp
@@ -24,10 +24,7 @@
 #include "ndn-cxx/security/transform/public-key.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace detail {
+namespace ndn::security::pib {
 
 NDN_LOG_INIT(ndn.security.Key);
 
@@ -103,7 +100,4 @@
   return *m_defaultCert;
 }
 
-} // namespace detail
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/impl/key-impl.hpp b/ndn-cxx/security/pib/impl/key-impl.hpp
index b6d73c6..74767e6 100644
--- a/ndn-cxx/security/pib/impl/key-impl.hpp
+++ b/ndn-cxx/security/pib/impl/key-impl.hpp
@@ -25,14 +25,10 @@
 #include "ndn-cxx/security/security-common.hpp"
 #include "ndn-cxx/security/pib/certificate-container.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 class PibImpl;
 
-namespace detail {
-
 /**
  * @brief Backend instance of Key.
  *
@@ -134,9 +130,6 @@
   mutable std::optional<Certificate> m_defaultCert;
 };
 
-} // namespace detail
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITY_PIB_IMPL_KEY_IMPL_HPP
diff --git a/ndn-cxx/security/pib/impl/pib-memory.cpp b/ndn-cxx/security/pib/impl/pib-memory.cpp
index 973d9d6..c75ffe3 100644
--- a/ndn-cxx/security/pib/impl/pib-memory.cpp
+++ b/ndn-cxx/security/pib/impl/pib-memory.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include <boost/range/adaptor/map.hpp>
 #include <boost/range/algorithm_ext/insert.hpp>
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 PibMemory::PibMemory(const std::string&)
 {
@@ -263,6 +261,4 @@
   return certIt->second;
 }
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/impl/pib-memory.hpp b/ndn-cxx/security/pib/impl/pib-memory.hpp
index a2e7abd..94fddb3 100644
--- a/ndn-cxx/security/pib/impl/pib-memory.hpp
+++ b/ndn-cxx/security/pib/impl/pib-memory.hpp
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/pib/pib-impl.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 /**
  * @brief An in-memory PIB implementation.
@@ -142,8 +140,6 @@
   std::map<Name, Certificate> m_certs;
 };
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITY_PIB_IMPL_PIB_MEMORY_HPP
diff --git a/ndn-cxx/security/pib/impl/pib-sqlite3.cpp b/ndn-cxx/security/pib/impl/pib-sqlite3.cpp
index 514f6de..938eada 100644
--- a/ndn-cxx/security/pib/impl/pib-sqlite3.cpp
+++ b/ndn-cxx/security/pib/impl/pib-sqlite3.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,11 +27,9 @@
 #include <boost/filesystem/operations.hpp>
 #include <boost/filesystem/path.hpp>
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
-using util::Sqlite3Statement;
+using ndn::util::Sqlite3Statement;
 
 static const char DB_INIT[] = R"SQL(
 CREATE TABLE IF NOT EXISTS
@@ -575,6 +573,4 @@
   return statement.step() == SQLITE_ROW;
 }
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/impl/pib-sqlite3.hpp b/ndn-cxx/security/pib/impl/pib-sqlite3.hpp
index 783a6a7..9313b26 100644
--- a/ndn-cxx/security/pib/impl/pib-sqlite3.hpp
+++ b/ndn-cxx/security/pib/impl/pib-sqlite3.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 
 struct sqlite3;
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 /**
  * @brief Pib backend implementation based on SQLite3 database
@@ -149,8 +147,6 @@
   sqlite3* m_database;
 };
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITTY_PIB_IMPL_PIB_SQLITE3_HPP
diff --git a/ndn-cxx/security/pib/key-container.cpp b/ndn-cxx/security/pib/key-container.cpp
index c13c133..94084ce 100644
--- a/ndn-cxx/security/pib/key-container.cpp
+++ b/ndn-cxx/security/pib/key-container.cpp
@@ -24,9 +24,7 @@
 #include "ndn-cxx/security/pib/pib-impl.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 NDN_LOG_INIT(ndn.security.KeyContainer);
 
@@ -80,7 +78,7 @@
   NDN_LOG_DEBUG((isNew ? "Adding " : "Replacing ") << keyName);
   m_pib->addKey(m_identity, keyName, keyBits);
 
-  auto key = std::make_shared<detail::KeyImpl>(keyName, Buffer(keyBits.begin(), keyBits.end()), m_pib);
+  auto key = std::make_shared<KeyImpl>(keyName, Buffer(keyBits.begin(), keyBits.end()), m_pib);
   m_keys[keyName] = key; // use insert_or_assign in C++17
   return Key(key);
 }
@@ -120,7 +118,7 @@
   // because getKeyBits will throw if it doesn't
   auto keyBits = m_pib->getKeyBits(keyName);
 
-  auto key = std::make_shared<detail::KeyImpl>(keyName, std::move(keyBits), m_pib);
+  auto key = std::make_shared<KeyImpl>(keyName, std::move(keyBits), m_pib);
   m_keys[keyName] = key;
   return Key(key);
 }
@@ -131,6 +129,4 @@
   return m_keyNames == m_pib->getKeysOfIdentity(m_identity);
 }
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/key-container.hpp b/ndn-cxx/security/pib/key-container.hpp
index cb9b211..2b9b36c 100644
--- a/ndn-cxx/security/pib/key-container.hpp
+++ b/ndn-cxx/security/pib/key-container.hpp
@@ -28,17 +28,10 @@
 #include <set>
 #include <unordered_map>
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 class PibImpl;
 
-namespace detail {
-class IdentityImpl;
-class KeyImpl;
-} // namespace detail
-
 /**
  * @brief Container of keys of an identity.
  *
@@ -178,18 +171,16 @@
 
 NDN_CXX_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   // cache of loaded KeyImpl
-  mutable std::unordered_map<Name, shared_ptr<detail::KeyImpl>> m_keys;
+  mutable std::unordered_map<Name, shared_ptr<KeyImpl>> m_keys;
 
 private:
   NameSet m_keyNames;
   const Name m_identity;
   const shared_ptr<PibImpl> m_pib;
 
-  friend detail::IdentityImpl;
+  friend class IdentityImpl;
 };
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITY_PIB_KEY_CONTAINER_HPP
diff --git a/ndn-cxx/security/pib/key.cpp b/ndn-cxx/security/pib/key.cpp
index 8dbb35e..69f96d0 100644
--- a/ndn-cxx/security/pib/key.cpp
+++ b/ndn-cxx/security/pib/key.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,13 +22,12 @@
 #include "ndn-cxx/security/pib/key.hpp"
 #include "ndn-cxx/security/pib/impl/key-impl.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 namespace pib {
 
 Key::Key() noexcept = default;
 
-Key::Key(weak_ptr<detail::KeyImpl> impl) noexcept
+Key::Key(weak_ptr<KeyImpl> impl) noexcept
   : m_impl(std::move(impl))
 {
 }
@@ -104,7 +103,7 @@
   return !m_impl.expired();
 }
 
-shared_ptr<detail::KeyImpl>
+shared_ptr<KeyImpl>
 Key::lock() const
 {
   auto impl = m_impl.lock();
@@ -123,8 +122,6 @@
 
 } // namespace pib
 
-inline namespace v2 {
-
 Name
 constructKeyName(const Name& identity, const name::Component& keyId)
 {
@@ -151,6 +148,4 @@
   return keyName.getPrefix(-Certificate::MIN_KEY_NAME_LENGTH); // trim everything after and including "KEY"
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/pib/key.hpp b/ndn-cxx/security/pib/key.hpp
index 124ddc5..bd548fa 100644
--- a/ndn-cxx/security/pib/key.hpp
+++ b/ndn-cxx/security/pib/key.hpp
@@ -25,20 +25,14 @@
 #include "ndn-cxx/security/pib/certificate-container.hpp"
 #include "ndn-cxx/security/security-common.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
-inline namespace v2 {
 class KeyChain;
-} // inline namespace v2
 
 namespace pib {
 
 class KeyContainer;
-
-namespace detail {
 class KeyImpl;
-} // namespace detail
 
 /**
  * @brief Frontend handle for a key in the PIB.
@@ -162,7 +156,7 @@
 
 NDN_CXX_PUBLIC_WITH_TESTS_ELSE_PRIVATE: // private interface for KeyContainer
   explicit
-  Key(weak_ptr<detail::KeyImpl> impl) noexcept;
+  Key(weak_ptr<KeyImpl> impl) noexcept;
 
 private:
   /**
@@ -170,7 +164,7 @@
    * @return a shared_ptr when the instance is valid
    * @throw std::domain_error the instance is invalid
    */
-  shared_ptr<detail::KeyImpl>
+  shared_ptr<KeyImpl>
   lock() const;
 
   bool
@@ -202,7 +196,7 @@
   }
 
 private:
-  weak_ptr<detail::KeyImpl> m_impl;
+  weak_ptr<KeyImpl> m_impl;
 
   friend KeyChain;
   friend KeyContainer;
@@ -212,8 +206,6 @@
 
 using pib::Key;
 
-inline namespace v2 {
-
 /**
  * @brief Construct key name based on the appropriate naming conventions
  */
@@ -232,8 +224,6 @@
 Name
 extractIdentityFromKeyName(const Name& keyName);
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_PIB_KEY_HPP
diff --git a/ndn-cxx/security/pib/pib-impl.hpp b/ndn-cxx/security/pib/pib-impl.hpp
index 3cad8e4..115b24e 100644
--- a/ndn-cxx/security/pib/pib-impl.hpp
+++ b/ndn-cxx/security/pib/pib-impl.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,7 @@
 
 #include <set>
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 /**
  * @brief PIB backend interface.
@@ -276,8 +274,6 @@
   getDefaultCertificateOfKey(const Name& keyName) const = 0;
 };
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
 
 #endif // NDN_CXX_SECURITY_PIB_PIB_IMPL_HPP
diff --git a/ndn-cxx/security/pib/pib.cpp b/ndn-cxx/security/pib/pib.cpp
index 8fb52cc..0810ba8 100644
--- a/ndn-cxx/security/pib/pib.cpp
+++ b/ndn-cxx/security/pib/pib.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,7 @@
 #include "ndn-cxx/security/pib/pib-impl.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
+namespace ndn::security::pib {
 
 NDN_LOG_INIT(ndn.security.Pib);
 
@@ -127,6 +125,4 @@
   return m_defaultIdentity;
 }
 
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::pib
diff --git a/ndn-cxx/security/pib/pib.hpp b/ndn-cxx/security/pib/pib.hpp
index 4ae4c8d..331bb79 100644
--- a/ndn-cxx/security/pib/pib.hpp
+++ b/ndn-cxx/security/pib/pib.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/security/pib/identity-container.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 namespace pib {
 
 class PibImpl;
@@ -160,7 +159,6 @@
 
 using pib::Pib;
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_PIB_PIB_HPP
diff --git a/ndn-cxx/security/safe-bag.cpp b/ndn-cxx/security/safe-bag.cpp
index b6e6997..6662980 100644
--- a/ndn-cxx/security/safe-bag.cpp
+++ b/ndn-cxx/security/safe-bag.cpp
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/encoding-buffer.hpp"
 #include "ndn-cxx/encoding/tlv-security.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 SafeBag::SafeBag() = default;
 
@@ -108,5 +107,4 @@
   }
 }
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/safe-bag.hpp b/ndn-cxx/security/safe-bag.hpp
index 3e580a3..0d402ca 100644
--- a/ndn-cxx/security/safe-bag.hpp
+++ b/ndn-cxx/security/safe-bag.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 #include "ndn-cxx/encoding/block.hpp"
 #include "ndn-cxx/encoding/buffer.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 /**
  * @brief A secured container for sensitive information (certificate, private key)
@@ -104,7 +103,6 @@
 
 NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(SafeBag);
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_SAFE_BAG_HPP
diff --git a/ndn-cxx/security/security-common.hpp b/ndn-cxx/security/security-common.hpp
index aedee38..8100a7c 100644
--- a/ndn-cxx/security/security-common.hpp
+++ b/ndn-cxx/security/security-common.hpp
@@ -31,11 +31,15 @@
 
 namespace signed_interest {
 
+/// \deprecated The old Signed %Interest format is deprecated.
 inline constexpr ssize_t POS_SIG_VALUE = -1;
+/// \deprecated The old Signed %Interest format is deprecated.
 inline constexpr ssize_t POS_SIG_INFO = -2;
 
-/** \brief Minimum number of name components for an old-style Signed %Interest.
- *  \sa https://redmine.named-data.net/projects/ndn-cxx/wiki/SignedInterest
+/**
+ * \brief Minimum number of name components for an old-style Signed %Interest.
+ * \deprecated The old Signed %Interest format is deprecated.
+ * \sa https://redmine.named-data.net/projects/ndn-cxx/wiki/SignedInterest
  */
 inline constexpr size_t MIN_SIZE = 2;
 
@@ -43,13 +47,19 @@
 
 namespace command_interest {
 
-using signed_interest::POS_SIG_VALUE;
-using signed_interest::POS_SIG_INFO;
+/// \deprecated The Command %Interest format is deprecated.
+inline constexpr ssize_t POS_SIG_VALUE = -1;
+/// \deprecated The Command %Interest format is deprecated.
+inline constexpr ssize_t POS_SIG_INFO = -2;
+/// \deprecated The Command %Interest format is deprecated.
 inline constexpr ssize_t POS_RANDOM_VAL = -3;
+/// \deprecated The Command %Interest format is deprecated.
 inline constexpr ssize_t POS_TIMESTAMP = -4;
 
-/** \brief Minimum number of name components for a Command %Interest.
- *  \sa https://redmine.named-data.net/projects/ndn-cxx/wiki/CommandInterest
+/**
+ * \brief Minimum number of name components for a Command %Interest.
+ * \deprecated The Command %Interest format is deprecated.
+ * \sa https://redmine.named-data.net/projects/ndn-cxx/wiki/CommandInterest
  */
 inline constexpr size_t MIN_SIZE = 4;
 
diff --git a/ndn-cxx/security/signing-helpers.cpp b/ndn-cxx/security/signing-helpers.cpp
index a81097f..14c184e 100644
--- a/ndn-cxx/security/signing-helpers.cpp
+++ b/ndn-cxx/security/signing-helpers.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,8 +21,7 @@
 
 #include "ndn-cxx/security/signing-helpers.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 SigningInfo
 signingByIdentity(const Name& identityName)
@@ -66,5 +65,4 @@
   return SigningInfo(SigningInfo::SIGNER_TYPE_SHA256);
 }
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/signing-info.cpp b/ndn-cxx/security/signing-info.cpp
index 1fd152f..d587606 100644
--- a/ndn-cxx/security/signing-info.cpp
+++ b/ndn-cxx/security/signing-info.cpp
@@ -26,8 +26,7 @@
 #include "ndn-cxx/security/transform/buffer-source.hpp"
 #include "ndn-cxx/security/transform/stream-sink.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 const Name&
 SigningInfo::getDigestSha256Identity()
@@ -215,5 +214,4 @@
   return os << "Unknown signed Interest format " << to_underlying(format);
 }
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/signing-info.hpp b/ndn-cxx/security/signing-info.hpp
index 1cf56fa..b9d45f2 100644
--- a/ndn-cxx/security/signing-info.hpp
+++ b/ndn-cxx/security/signing-info.hpp
@@ -29,8 +29,7 @@
 #include "ndn-cxx/security/security-common.hpp"
 #include "ndn-cxx/security/transform/private-key.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 /**
  * @note This is a transitional API to handle the change in signed Interest format and will
@@ -320,7 +319,6 @@
 std::ostream&
 operator<<(std::ostream& os, const SignedInterestFormat& format);
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_SIGNING_INFO_HPP
diff --git a/ndn-cxx/security/tpm/back-end.cpp b/ndn-cxx/security/tpm/back-end.cpp
index f8f450a..d336b0b 100644
--- a/ndn-cxx/security/tpm/back-end.cpp
+++ b/ndn-cxx/security/tpm/back-end.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,9 +31,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 BackEnd::~BackEnd() = default;
 
@@ -170,6 +168,4 @@
   return !isTpmLocked();
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/back-end.hpp b/ndn-cxx/security/tpm/back-end.hpp
index dfe50cd..b66d267 100644
--- a/ndn-cxx/security/tpm/back-end.hpp
+++ b/ndn-cxx/security/tpm/back-end.hpp
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/tpm/tpm.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 /**
  * @brief Abstract interface for a TPM backend implementation.
@@ -196,8 +194,6 @@
   doImportKey(const Name& keyName, shared_ptr<transform::PrivateKey> key) = 0;
 };
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
 
 #endif // NDN_CXX_SECURITY_TPM_BACK_END_HPP
diff --git a/ndn-cxx/security/tpm/impl/back-end-file.cpp b/ndn-cxx/security/tpm/impl/back-end-file.cpp
index 8bf11b4..4c466d1 100644
--- a/ndn-cxx/security/tpm/impl/back-end-file.cpp
+++ b/ndn-cxx/security/tpm/impl/back-end-file.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -36,12 +36,10 @@
 #include <boost/filesystem/path.hpp>
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 namespace fs = boost::filesystem;
-using transform::PrivateKey;
+using ndn::security::transform::PrivateKey;
 
 class BackEndFile::Impl
 {
@@ -226,6 +224,4 @@
   ::chmod(fileName.data(), 0000400);
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/impl/back-end-file.hpp b/ndn-cxx/security/tpm/impl/back-end-file.hpp
index 6841681..18657dd 100644
--- a/ndn-cxx/security/tpm/impl/back-end-file.hpp
+++ b/ndn-cxx/security/tpm/impl/back-end-file.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/security/tpm/back-end.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 namespace transform {
 class PrivateKey;
@@ -96,7 +95,6 @@
 };
 
 } // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_TPM_IMPL_BACK_END_FILE_HPP
diff --git a/ndn-cxx/security/tpm/impl/back-end-mem.cpp b/ndn-cxx/security/tpm/impl/back-end-mem.cpp
index ec9828b..e69dd19 100644
--- a/ndn-cxx/security/tpm/impl/back-end-mem.cpp
+++ b/ndn-cxx/security/tpm/impl/back-end-mem.cpp
@@ -28,11 +28,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
-using transform::PrivateKey;
+using ndn::security::transform::PrivateKey;
 
 class BackEndMem::Impl
 {
@@ -131,6 +129,4 @@
   m_impl->keys[keyName] = std::move(key);
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/impl/back-end-mem.hpp b/ndn-cxx/security/tpm/impl/back-end-mem.hpp
index 176833b..3760308 100644
--- a/ndn-cxx/security/tpm/impl/back-end-mem.hpp
+++ b/ndn-cxx/security/tpm/impl/back-end-mem.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/tpm/back-end.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 /**
  * @brief The back-end implementation of an in-memory TPM.
@@ -74,8 +72,6 @@
   const unique_ptr<Impl> m_impl;
 };
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
 
 #endif // NDN_CXX_SECURITY_TPM_IMPL_BACK_END_MEM_HPP
diff --git a/ndn-cxx/security/tpm/impl/back-end-osx.cpp b/ndn-cxx/security/tpm/impl/back-end-osx.cpp
index 654d957..0567655 100644
--- a/ndn-cxx/security/tpm/impl/back-end-osx.cpp
+++ b/ndn-cxx/security/tpm/impl/back-end-osx.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -33,12 +33,10 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
-namespace cfstring = detail::cfstring;
-using detail::CFReleaser;
+namespace cfstring = ndn::detail::cfstring;
+using ndn::detail::CFReleaser;
 
 class BackEndOsx::Impl
 {
@@ -522,6 +520,4 @@
   NDN_THROW(Error("macOS-based TPM does not support importing a transform::PrivateKey"));
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/impl/back-end-osx.hpp b/ndn-cxx/security/tpm/impl/back-end-osx.hpp
index eda536e..706bca4 100644
--- a/ndn-cxx/security/tpm/impl/back-end-osx.hpp
+++ b/ndn-cxx/security/tpm/impl/back-end-osx.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,9 +30,7 @@
 
 #include "ndn-cxx/security/tpm/impl/key-ref-osx.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 /**
  * @brief The back-end implementation of TPM based on macOS Keychain Services.
@@ -109,8 +107,6 @@
   const unique_ptr<Impl> m_impl;
 };
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
 
 #endif // NDN_CXX_SECURITY_TPM_IMPL_BACK_END_OSX_HPP
diff --git a/ndn-cxx/security/tpm/impl/key-handle-mem.cpp b/ndn-cxx/security/tpm/impl/key-handle-mem.cpp
index 9a801e3..3455c3f 100644
--- a/ndn-cxx/security/tpm/impl/key-handle-mem.cpp
+++ b/ndn-cxx/security/tpm/impl/key-handle-mem.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,9 +28,7 @@
 #include "ndn-cxx/security/transform/verifier-filter.hpp"
 #include "ndn-cxx/encoding/buffer-stream.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 KeyHandleMem::KeyHandleMem(shared_ptr<transform::PrivateKey> key)
   : m_key(std::move(key))
@@ -72,6 +70,4 @@
   return m_key->derivePublicKey();
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/impl/key-handle-mem.hpp b/ndn-cxx/security/tpm/impl/key-handle-mem.hpp
index 07516da..22bcbca 100644
--- a/ndn-cxx/security/tpm/impl/key-handle-mem.hpp
+++ b/ndn-cxx/security/tpm/impl/key-handle-mem.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/security/tpm/key-handle.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 namespace transform {
 class PrivateKey;
@@ -60,7 +59,6 @@
 };
 
 } // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_TPM_IMPL_KEY_HANDLE_MEM_HPP
diff --git a/ndn-cxx/security/tpm/impl/key-handle-osx.cpp b/ndn-cxx/security/tpm/impl/key-handle-osx.cpp
index db43fa4..623529c 100644
--- a/ndn-cxx/security/tpm/impl/key-handle-osx.cpp
+++ b/ndn-cxx/security/tpm/impl/key-handle-osx.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,9 +22,7 @@
 #include "ndn-cxx/security/tpm/impl/key-handle-osx.hpp"
 #include "ndn-cxx/security/tpm/impl/back-end-osx.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 KeyHandleOsx::KeyHandleOsx(const KeyRefOsx& key)
   : m_key(key)
@@ -57,6 +55,4 @@
   return BackEndOsx::derivePublicKey(m_key);
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/impl/key-handle-osx.hpp b/ndn-cxx/security/tpm/impl/key-handle-osx.hpp
index 49bd655..40f1762 100644
--- a/ndn-cxx/security/tpm/impl/key-handle-osx.hpp
+++ b/ndn-cxx/security/tpm/impl/key-handle-osx.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,9 +30,7 @@
 
 #include "ndn-cxx/security/tpm/impl/key-ref-osx.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 /**
  * @brief Abstraction of TPM key handle used by the TPM based on macOS Keychain Services.
@@ -61,8 +59,6 @@
   KeyRefOsx m_key;
 };
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
 
 #endif // NDN_CXX_SECURITY_TPM_IMPL_KEY_HANDLE_OSX_HPP
diff --git a/ndn-cxx/security/tpm/impl/key-ref-osx.hpp b/ndn-cxx/security/tpm/impl/key-ref-osx.hpp
index 88345b2..c3ad98d 100644
--- a/ndn-cxx/security/tpm/impl/key-ref-osx.hpp
+++ b/ndn-cxx/security/tpm/impl/key-ref-osx.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -32,14 +32,10 @@
 
 #include <Security/Security.h>
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 using KeyRefOsx = detail::CFReleaser<SecKeyRef>;
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
 
 #endif // NDN_CXX_SECURITY_TPM_IMPL_KEY_REF_OSX_HPP
diff --git a/ndn-cxx/security/tpm/key-handle.cpp b/ndn-cxx/security/tpm/key-handle.cpp
index 13af2b0..4e18fe5 100644
--- a/ndn-cxx/security/tpm/key-handle.cpp
+++ b/ndn-cxx/security/tpm/key-handle.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/tpm/key-handle.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 KeyHandle::~KeyHandle() = default;
 
@@ -52,6 +50,4 @@
   return doDerivePublicKey();
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/key-handle.hpp b/ndn-cxx/security/tpm/key-handle.hpp
index d718e54..3b3161f 100644
--- a/ndn-cxx/security/tpm/key-handle.hpp
+++ b/ndn-cxx/security/tpm/key-handle.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/name.hpp"
 #include "ndn-cxx/security/security-common.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 /**
  * @brief Abstraction of TPM key handle.
@@ -100,8 +98,6 @@
   Name m_keyName;
 };
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
 
 #endif // NDN_CXX_SECURITY_TPM_KEY_HANDLE_HPP
diff --git a/ndn-cxx/security/tpm/tpm.cpp b/ndn-cxx/security/tpm/tpm.cpp
index ded3ca8..9e150de 100644
--- a/ndn-cxx/security/tpm/tpm.cpp
+++ b/ndn-cxx/security/tpm/tpm.cpp
@@ -25,9 +25,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace tpm {
+namespace ndn::security::tpm {
 
 Tpm::Tpm(const std::string& locator, unique_ptr<BackEnd> backEnd)
   : m_locator(locator)
@@ -150,6 +148,4 @@
   return key;
 }
 
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::tpm
diff --git a/ndn-cxx/security/tpm/tpm.hpp b/ndn-cxx/security/tpm/tpm.hpp
index 1ffdeb1..feae793 100644
--- a/ndn-cxx/security/tpm/tpm.hpp
+++ b/ndn-cxx/security/tpm/tpm.hpp
@@ -29,16 +29,13 @@
 #include <unordered_map>
 #include <boost/logic/tribool.hpp>
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 namespace transform {
 class PrivateKey;
 } // namespace transform
 
-inline namespace v2 {
 class KeyChain;
-} // inline namespace v2
 
 namespace tpm {
 
@@ -256,7 +253,6 @@
 
 using tpm::Tpm;
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_TPM_TPM_HPP
diff --git a/ndn-cxx/security/transform/base64-decode.cpp b/ndn-cxx/security/transform/base64-decode.cpp
index e9a3f08..1554ccb 100644
--- a/ndn-cxx/security/transform/base64-decode.cpp
+++ b/ndn-cxx/security/transform/base64-decode.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 #include <openssl/bio.h>
 #include <openssl/evp.h>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class Base64Decode::Impl : boost::noncopyable
 {
@@ -128,6 +126,4 @@
   return make_unique<Base64Decode>(expectNewlineEvery64Bytes);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/base64-decode.hpp b/ndn-cxx/security/transform/base64-decode.hpp
index 38949d3..b2aa0fb 100644
--- a/ndn-cxx/security/transform/base64-decode.hpp
+++ b/ndn-cxx/security/transform/base64-decode.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief The module to perform Base64 decoding transformation.
@@ -82,8 +80,6 @@
 unique_ptr<Transform>
 base64Decode(bool expectNewlineEvery64Bytes = true);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_BASE64_DECODE_HPP
diff --git a/ndn-cxx/security/transform/base64-encode.cpp b/ndn-cxx/security/transform/base64-encode.cpp
index 5383a8f..af56408 100644
--- a/ndn-cxx/security/transform/base64-encode.cpp
+++ b/ndn-cxx/security/transform/base64-encode.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 #include <openssl/bio.h>
 #include <openssl/evp.h>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class Base64Encode::Impl : boost::noncopyable
 {
@@ -131,6 +129,4 @@
   return make_unique<Base64Encode>(needBreak);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/base64-encode.hpp b/ndn-cxx/security/transform/base64-encode.hpp
index 1c09376..874fda0 100644
--- a/ndn-cxx/security/transform/base64-encode.hpp
+++ b/ndn-cxx/security/transform/base64-encode.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief The module to perform Base64 encoding transformation.
@@ -86,8 +84,6 @@
 unique_ptr<Transform>
 base64Encode(bool needBreak = true);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_BASE64_ENCODE_HPP
diff --git a/ndn-cxx/security/transform/block-cipher.cpp b/ndn-cxx/security/transform/block-cipher.cpp
index bc881f1..e7cddc0 100644
--- a/ndn-cxx/security/transform/block-cipher.cpp
+++ b/ndn-cxx/security/transform/block-cipher.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class BlockCipher::Impl : boost::noncopyable
 {
@@ -164,6 +162,4 @@
   return make_unique<BlockCipher>(algo, op, key, iv);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/block-cipher.hpp b/ndn-cxx/security/transform/block-cipher.hpp
index ecde4e7..78d5bef 100644
--- a/ndn-cxx/security/transform/block-cipher.hpp
+++ b/ndn-cxx/security/transform/block-cipher.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/transform/transform-base.hpp"
 #include "ndn-cxx/security/security-common.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief The module to encrypt data using block cipher.
@@ -97,8 +95,6 @@
 blockCipher(BlockCipherAlgorithm algo, CipherOperator op,
             span<const uint8_t> key, span<const uint8_t> iv);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_BLOCK_CIPHER_HPP
diff --git a/ndn-cxx/security/transform/bool-sink.cpp b/ndn-cxx/security/transform/bool-sink.cpp
index c57cf77..3a86a0e 100644
--- a/ndn-cxx/security/transform/bool-sink.cpp
+++ b/ndn-cxx/security/transform/bool-sink.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/transform/bool-sink.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 BoolSink::BoolSink(bool& value)
   : m_hasValue(false)
@@ -53,6 +51,4 @@
   return make_unique<BoolSink>(value);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/bool-sink.hpp b/ndn-cxx/security/transform/bool-sink.hpp
index 827019a..bf4b4df 100644
--- a/ndn-cxx/security/transform/bool-sink.hpp
+++ b/ndn-cxx/security/transform/bool-sink.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief A sink which outputs only one boolean value.
@@ -66,8 +64,6 @@
 unique_ptr<Sink>
 boolSink(bool& value);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_BOOL_SINK_HPP
diff --git a/ndn-cxx/security/transform/buffer-source.cpp b/ndn-cxx/security/transform/buffer-source.cpp
index 8333368..c345e03 100644
--- a/ndn-cxx/security/transform/buffer-source.cpp
+++ b/ndn-cxx/security/transform/buffer-source.cpp
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/transform/buffer-source.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 BufferSource::BufferSource(span<const uint8_t> buffer)
   : m_bufs({buffer})
@@ -55,6 +53,4 @@
   m_next->end();
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/buffer-source.hpp b/ndn-cxx/security/transform/buffer-source.hpp
index 7d87320..bd0c34a 100644
--- a/ndn-cxx/security/transform/buffer-source.hpp
+++ b/ndn-cxx/security/transform/buffer-source.hpp
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/transform/transform-base.hpp"
 #include "ndn-cxx/security/security-common.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief A source taking one or more memory buffers as input
@@ -72,8 +70,6 @@
 
 using bufferSource = BufferSource;
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_BUFFER_SOURCE_HPP
diff --git a/ndn-cxx/security/transform/digest-filter.cpp b/ndn-cxx/security/transform/digest-filter.cpp
index 6462075..89e4917 100644
--- a/ndn-cxx/security/transform/digest-filter.cpp
+++ b/ndn-cxx/security/transform/digest-filter.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class DigestFilter::Impl
 {
@@ -78,6 +76,4 @@
   return make_unique<DigestFilter>(algo);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/digest-filter.hpp b/ndn-cxx/security/transform/digest-filter.hpp
index 30f96ec..26a2851 100644
--- a/ndn-cxx/security/transform/digest-filter.hpp
+++ b/ndn-cxx/security/transform/digest-filter.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/transform/transform-base.hpp"
 #include "ndn-cxx/security/security-common.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief The module to calculate digests.
@@ -66,8 +64,6 @@
 unique_ptr<Transform>
 digestFilter(DigestAlgorithm algo);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_DIGEST_FILTER_HPP
diff --git a/ndn-cxx/security/transform/hex-decode.cpp b/ndn-cxx/security/transform/hex-decode.cpp
index 6970a65..9cbccf7 100644
--- a/ndn-cxx/security/transform/hex-decode.cpp
+++ b/ndn-cxx/security/transform/hex-decode.cpp
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/transform/hex-decode.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 // hex decoding pad
 static const int8_t C2H[] = {
@@ -117,6 +115,4 @@
   return make_unique<HexDecode>();
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/hex-decode.hpp b/ndn-cxx/security/transform/hex-decode.hpp
index 43c7e71..72ffb18 100644
--- a/ndn-cxx/security/transform/hex-decode.hpp
+++ b/ndn-cxx/security/transform/hex-decode.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief The module to perform hexadecimal decoding transformation.
@@ -73,8 +71,6 @@
 unique_ptr<Transform>
 hexDecode();
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_HEX_DECODE_HPP
diff --git a/ndn-cxx/security/transform/hex-encode.cpp b/ndn-cxx/security/transform/hex-encode.cpp
index 204466f..0a9da8d 100644
--- a/ndn-cxx/security/transform/hex-encode.cpp
+++ b/ndn-cxx/security/transform/hex-encode.cpp
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/transform/hex-encode.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 static const uint8_t H2CL[] = {
   '0', '1', '2', '3', '4', '5', '6', '7',
@@ -72,6 +70,4 @@
   return make_unique<HexEncode>(useUpperCase);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/hex-encode.hpp b/ndn-cxx/security/transform/hex-encode.hpp
index 71031e8..4d334b4 100644
--- a/ndn-cxx/security/transform/hex-encode.hpp
+++ b/ndn-cxx/security/transform/hex-encode.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief The module to perform hexadecimal encoding transformation.
@@ -67,8 +65,6 @@
 unique_ptr<Transform>
 hexEncode(bool useUpperCase = false);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_HEX_ENCODE_HPP
diff --git a/ndn-cxx/security/transform/private-key.cpp b/ndn-cxx/security/transform/private-key.cpp
index 53501a9..0acb648 100644
--- a/ndn-cxx/security/transform/private-key.cpp
+++ b/ndn-cxx/security/transform/private-key.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -54,9 +54,7 @@
       NDN_THROW(Error("Private key has already been loaded")); \
   } while (false)
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class PrivateKey::Impl : noncopyable
 {
@@ -544,6 +542,4 @@
   }
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/private-key.hpp b/ndn-cxx/security/transform/private-key.hpp
index 3890a10..271ffd4 100644
--- a/ndn-cxx/security/transform/private-key.hpp
+++ b/ndn-cxx/security/transform/private-key.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -29,8 +29,7 @@
 
 class KeyParams;
 
-namespace security {
-namespace transform {
+namespace security::transform {
 
 /**
  * @brief Abstraction of private key in crypto transformation
@@ -290,8 +289,7 @@
 unique_ptr<PrivateKey>
 generatePrivateKey(const KeyParams& keyParams);
 
-} // namespace transform
-} // namespace security
+} // namespace security::transform
 } // namespace ndn
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_PRIVATE_KEY_HPP
diff --git a/ndn-cxx/security/transform/public-key.cpp b/ndn-cxx/security/transform/public-key.cpp
index 3291628..599fcc9 100644
--- a/ndn-cxx/security/transform/public-key.cpp
+++ b/ndn-cxx/security/transform/public-key.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -43,9 +43,7 @@
       NDN_THROW(Error("Public key has already been loaded")); \
   } while (false)
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class PublicKey::Impl : noncopyable
 {
@@ -207,6 +205,4 @@
   return out;
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/public-key.hpp b/ndn-cxx/security/transform/public-key.hpp
index bd1a0c8..b0b3104 100644
--- a/ndn-cxx/security/transform/public-key.hpp
+++ b/ndn-cxx/security/transform/public-key.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/security-common.hpp"
 #include "ndn-cxx/encoding/buffer.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief Abstraction of public key in crypto transformation
@@ -129,8 +127,6 @@
   const unique_ptr<Impl> m_impl;
 };
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_PUBLIC_KEY_HPP
diff --git a/ndn-cxx/security/transform/signer-filter.cpp b/ndn-cxx/security/transform/signer-filter.cpp
index 036a16b..2c25f5e 100644
--- a/ndn-cxx/security/transform/signer-filter.cpp
+++ b/ndn-cxx/security/transform/signer-filter.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class SignerFilter::Impl
 {
@@ -85,6 +83,4 @@
   return make_unique<SignerFilter>(algo, key);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/signer-filter.hpp b/ndn-cxx/security/transform/signer-filter.hpp
index 842ba10..e01705e 100644
--- a/ndn-cxx/security/transform/signer-filter.hpp
+++ b/ndn-cxx/security/transform/signer-filter.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/transform/transform-base.hpp"
 #include "ndn-cxx/security/security-common.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class PrivateKey;
 
@@ -67,8 +65,6 @@
 unique_ptr<Transform>
 signerFilter(DigestAlgorithm algo, const PrivateKey& key);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_SIGNER_FILTER_HPP
diff --git a/ndn-cxx/security/transform/step-source.cpp b/ndn-cxx/security/transform/step-source.cpp
index cfeac7a..16376e3 100644
--- a/ndn-cxx/security/transform/step-source.cpp
+++ b/ndn-cxx/security/transform/step-source.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/transform/step-source.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 size_t
 StepSource::write(span<const uint8_t> buf)
@@ -42,6 +40,4 @@
 {
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/step-source.hpp b/ndn-cxx/security/transform/step-source.hpp
index 2c08260..40d0548 100644
--- a/ndn-cxx/security/transform/step-source.hpp
+++ b/ndn-cxx/security/transform/step-source.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief A source that can accept input step by step, and can close input explicitly.
@@ -74,8 +72,6 @@
 
 using stepSource = StepSource;
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_STEP_SOURCE_HPP
diff --git a/ndn-cxx/security/transform/stream-sink.cpp b/ndn-cxx/security/transform/stream-sink.cpp
index c35e196..496a39c 100644
--- a/ndn-cxx/security/transform/stream-sink.cpp
+++ b/ndn-cxx/security/transform/stream-sink.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,7 @@
 
 #include <ostream>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 StreamSink::StreamSink(std::ostream& os)
   : m_os(os)
@@ -55,6 +53,4 @@
   return make_unique<StreamSink>(os);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/stream-sink.hpp b/ndn-cxx/security/transform/stream-sink.hpp
index d2e6e32..3ad37bd 100644
--- a/ndn-cxx/security/transform/stream-sink.hpp
+++ b/ndn-cxx/security/transform/stream-sink.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief A sink which directs output to an std::ostream.
@@ -59,8 +57,6 @@
 unique_ptr<Sink>
 streamSink(std::ostream& os);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_STREAM_SINK_HPP
diff --git a/ndn-cxx/security/transform/stream-source.cpp b/ndn-cxx/security/transform/stream-source.cpp
index 10e5fa6..c9674e9 100644
--- a/ndn-cxx/security/transform/stream-source.cpp
+++ b/ndn-cxx/security/transform/stream-source.cpp
@@ -24,9 +24,7 @@
 #include <istream>
 #include <vector>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 StreamSource::StreamSource(std::istream& is, size_t bufferSize)
   : Source()
@@ -65,6 +63,4 @@
   m_next->end();
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/stream-source.hpp b/ndn-cxx/security/transform/stream-source.hpp
index 886066b..02a66e4 100644
--- a/ndn-cxx/security/transform/stream-source.hpp
+++ b/ndn-cxx/security/transform/stream-source.hpp
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @brief A source taking an std::istream as input
@@ -59,10 +57,8 @@
   size_t m_bufferSize;
 };
 
-typedef StreamSource streamSource;
+using streamSource = StreamSource;
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_STREAM_SOURCE_HPP
diff --git a/ndn-cxx/security/transform/strip-space.cpp b/ndn-cxx/security/transform/strip-space.cpp
index 9465400..12b43d9 100644
--- a/ndn-cxx/security/transform/strip-space.cpp
+++ b/ndn-cxx/security/transform/strip-space.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/transform/strip-space.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 const char* const StripSpace::DEFAULT_WHITESPACES = " \f\n\r\t\v";
 
@@ -56,6 +54,4 @@
   return make_unique<StripSpace>(whitespaces);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/strip-space.hpp b/ndn-cxx/security/transform/strip-space.hpp
index f01e936..1c1e119 100644
--- a/ndn-cxx/security/transform/strip-space.hpp
+++ b/ndn-cxx/security/transform/strip-space.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,7 @@
 #include <bitset>
 #include <climits>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * \brief Strip whitespace characters from a stream.
@@ -60,8 +58,6 @@
 unique_ptr<Transform>
 stripSpace(const char* whitespaces = StripSpace::DEFAULT_WHITESPACES);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_STRIP_SPACE_HPP
diff --git a/ndn-cxx/security/transform/transform-base.cpp b/ndn-cxx/security/transform/transform-base.cpp
index 731b22c..2abcfb4 100644
--- a/ndn-cxx/security/transform/transform-base.cpp
+++ b/ndn-cxx/security/transform/transform-base.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/transform/transform-base.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 Error::Error(size_t index, const std::string& what)
   : std::runtime_error("Error in module " + to_string(index) + ": " + what)
@@ -157,6 +155,4 @@
   pump();
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/transform-base.hpp b/ndn-cxx/security/transform/transform-base.hpp
index faf96be..15548c7 100644
--- a/ndn-cxx/security/transform/transform-base.hpp
+++ b/ndn-cxx/security/transform/transform-base.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,7 @@
 
 #include <vector>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 /**
  * @file
@@ -318,8 +316,6 @@
   size_t m_nModules = 1; // count of modules in the chain starting from (and including) this Source
 };
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_BASE_HPP
diff --git a/ndn-cxx/security/transform/verifier-filter.cpp b/ndn-cxx/security/transform/verifier-filter.cpp
index 4d4c6f0..4893c4c 100644
--- a/ndn-cxx/security/transform/verifier-filter.cpp
+++ b/ndn-cxx/security/transform/verifier-filter.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class VerifierFilter::Impl
 {
@@ -135,6 +133,4 @@
   return make_unique<VerifierFilter>(algo, key, sig);
 }
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
diff --git a/ndn-cxx/security/transform/verifier-filter.hpp b/ndn-cxx/security/transform/verifier-filter.hpp
index d5072f6..da2ae10 100644
--- a/ndn-cxx/security/transform/verifier-filter.hpp
+++ b/ndn-cxx/security/transform/verifier-filter.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/transform/transform-base.hpp"
 #include "ndn-cxx/security/security-common.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
+namespace ndn::security::transform {
 
 class PrivateKey;
 class PublicKey;
@@ -83,8 +81,6 @@
 unique_ptr<Transform>
 verifierFilter(DigestAlgorithm algo, const PrivateKey& key, span<const uint8_t> sig);
 
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::transform
 
 #endif // NDN_CXX_SECURITY_TRANSFORM_VERIFIER_FILTER_HPP
diff --git a/ndn-cxx/security/trust-anchor-container.cpp b/ndn-cxx/security/trust-anchor-container.cpp
index ccd123a..93856bf 100644
--- a/ndn-cxx/security/trust-anchor-container.cpp
+++ b/ndn-cxx/security/trust-anchor-container.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/trust-anchor-container.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 void
 TrustAnchorContainer::AnchorContainer::add(Certificate&& cert)
@@ -128,6 +126,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/trust-anchor-container.hpp b/ndn-cxx/security/trust-anchor-container.hpp
index 18afa36..6fe208d 100644
--- a/ndn-cxx/security/trust-anchor-container.hpp
+++ b/ndn-cxx/security/trust-anchor-container.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,9 +31,7 @@
 #include <boost/multi_index/ordered_index.hpp>
 #include <boost/multi_index/mem_fun.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief A container for trust anchors.
@@ -172,8 +170,6 @@
   AnchorContainer m_anchors;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_TRUST_ANCHOR_CONTAINER_HPP
diff --git a/ndn-cxx/security/trust-anchor-group.cpp b/ndn-cxx/security/trust-anchor-group.cpp
index 565c760..d3eaf92 100644
--- a/ndn-cxx/security/trust-anchor-group.cpp
+++ b/ndn-cxx/security/trust-anchor-group.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,9 +31,7 @@
 #include <boost/range/algorithm/copy.hpp>
 #include <boost/range/iterator_range.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 NDN_LOG_INIT(ndn.security.TrustAnchorGroup);
 
@@ -141,6 +139,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/trust-anchor-group.hpp b/ndn-cxx/security/trust-anchor-group.hpp
index 7c7198e..afd5aa2 100644
--- a/ndn-cxx/security/trust-anchor-group.hpp
+++ b/ndn-cxx/security/trust-anchor-group.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,9 +28,7 @@
 #include <boost/filesystem/path.hpp>
 #include <set>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 class CertContainerInterface
 {
@@ -160,11 +158,9 @@
   bool m_isDir;
   boost::filesystem::path m_path;
   time::nanoseconds m_refreshPeriod;
-  time::steady_clock::TimePoint m_expireTime;
+  time::steady_clock::time_point m_expireTime;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_TRUST_ANCHOR_GROUP_HPP
diff --git a/ndn-cxx/security/validation-callback.hpp b/ndn-cxx/security/validation-callback.hpp
index 8e00c33..ef7d8d2 100644
--- a/ndn-cxx/security/validation-callback.hpp
+++ b/ndn-cxx/security/validation-callback.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 #include "ndn-cxx/interest.hpp"
 #include "ndn-cxx/security/validation-error.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Callback to report a successful Data validation.
@@ -50,8 +48,6 @@
  */
 using InterestValidationFailureCallback = std::function<void(const Interest&, const ValidationError&)>;
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_CALLBACK_HPP
diff --git a/ndn-cxx/security/validation-error.cpp b/ndn-cxx/security/validation-error.cpp
index 7ab3abe..82ec2f7 100644
--- a/ndn-cxx/security/validation-error.cpp
+++ b/ndn-cxx/security/validation-error.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/validation-error.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 std::ostream&
 operator<<(std::ostream& os, ValidationError::Code code)
@@ -71,6 +69,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validation-error.hpp b/ndn-cxx/security/validation-error.hpp
index 07a1aaa..9adac22 100644
--- a/ndn-cxx/security/validation-error.hpp
+++ b/ndn-cxx/security/validation-error.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/detail/common.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Validation error code and optional detailed error message
@@ -109,8 +107,6 @@
 std::ostream&
 operator<<(std::ostream& os, ValidationError::Code code);
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_ERROR_HPP
diff --git a/ndn-cxx/security/validation-policy-accept-all.hpp b/ndn-cxx/security/validation-policy-accept-all.hpp
index 623a57f..a877ad1 100644
--- a/ndn-cxx/security/validation-policy-accept-all.hpp
+++ b/ndn-cxx/security/validation-policy-accept-all.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/validation-policy.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief A validator policy that accepts any signature of data and interest packets
@@ -49,8 +47,6 @@
   }
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_POLICY_ACCEPT_ALL_HPP
diff --git a/ndn-cxx/security/validation-policy-command-interest.cpp b/ndn-cxx/security/validation-policy-command-interest.cpp
index adf8bd1..ddae489 100644
--- a/ndn-cxx/security/validation-policy-command-interest.cpp
+++ b/ndn-cxx/security/validation-policy-command-interest.cpp
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/validation-policy-command-interest.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 ValidationPolicyCommandInterest::ValidationPolicyCommandInterest(unique_ptr<ValidationPolicy> inner,
                                                                  const Options& options)
@@ -171,6 +169,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validation-policy-command-interest.hpp b/ndn-cxx/security/validation-policy-command-interest.hpp
index d8fe1d0..959b80e 100644
--- a/ndn-cxx/security/validation-policy-command-interest.hpp
+++ b/ndn-cxx/security/validation-policy-command-interest.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -29,9 +29,7 @@
 #include <boost/multi_index/sequenced_index.hpp>
 #include <boost/multi_index/key_extractors.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Validation policy for stop-and-wait command Interests.
@@ -114,7 +112,7 @@
               const ValidationContinuation& continueValidation) override;
 
 private:
-  static std::tuple<bool, Name, time::system_clock::TimePoint>
+  static std::tuple<bool, Name, time::system_clock::time_point>
   parseCommandInterest(const Interest& interest, const shared_ptr<ValidationState>& state);
 
   void
@@ -122,10 +120,10 @@
 
   bool
   checkTimestamp(const shared_ptr<ValidationState>& state,
-                 const Name& keyName, time::system_clock::TimePoint timestamp);
+                 const Name& keyName, time::system_clock::time_point timestamp);
 
   void
-  insertNewRecord(const Name& keyName, time::system_clock::TimePoint timestamp);
+  insertNewRecord(const Name& keyName, time::system_clock::time_point timestamp);
 
 private:
   Options m_options;
@@ -133,8 +131,8 @@
   struct LastTimestampRecord
   {
     Name keyName;
-    time::system_clock::TimePoint timestamp;
-    time::steady_clock::TimePoint lastRefreshed;
+    time::system_clock::time_point timestamp;
+    time::steady_clock::time_point lastRefreshed;
   };
 
   using Container = boost::multi_index_container<
@@ -154,8 +152,6 @@
   Queue& m_queue;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_POLICY_COMMAND_INTEREST_HPP
diff --git a/ndn-cxx/security/validation-policy-config.cpp b/ndn-cxx/security/validation-policy-config.cpp
index 45bc867..29d0a86 100644
--- a/ndn-cxx/security/validation-policy-config.cpp
+++ b/ndn-cxx/security/validation-policy-config.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,10 +31,7 @@
 
 #include <fstream>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
+namespace ndn::security::validator_config {
 
 void
 ValidationPolicyConfig::load(const std::string& filename)
@@ -298,7 +295,4 @@
                       "No rule matched for interest `" + interest.getName().toUri() + "`"});
 }
 
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::validator_config
diff --git a/ndn-cxx/security/validation-policy-config.hpp b/ndn-cxx/security/validation-policy-config.hpp
index bc4b9f5..07e73e3 100644
--- a/ndn-cxx/security/validation-policy-config.hpp
+++ b/ndn-cxx/security/validation-policy-config.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/validation-policy.hpp"
 #include "ndn-cxx/security/validator-config/rule.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 namespace validator_config {
 
 /**
@@ -106,8 +104,6 @@
 
 using validator_config::ValidationPolicyConfig;
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_POLICY_CONFIG_HPP
diff --git a/ndn-cxx/security/validation-policy-signed-interest.cpp b/ndn-cxx/security/validation-policy-signed-interest.cpp
index 8071a3c..58f5779 100644
--- a/ndn-cxx/security/validation-policy-signed-interest.cpp
+++ b/ndn-cxx/security/validation-policy-signed-interest.cpp
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/validation-policy-signed-interest.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 ValidationPolicySignedInterest::ValidationPolicySignedInterest(unique_ptr<ValidationPolicy> inner,
                                                                const Options& options)
@@ -142,7 +140,7 @@
 
 void
 ValidationPolicySignedInterest::insertRecord(const Name& keyName,
-                                             std::optional<time::system_clock::TimePoint> timestamp,
+                                             std::optional<time::system_clock::time_point> timestamp,
                                              std::optional<uint64_t> seqNum,
                                              std::optional<SigNonce> nonce)
 {
@@ -185,6 +183,4 @@
   }
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validation-policy-signed-interest.hpp b/ndn-cxx/security/validation-policy-signed-interest.hpp
index 92365cd..39b5cc7 100644
--- a/ndn-cxx/security/validation-policy-signed-interest.hpp
+++ b/ndn-cxx/security/validation-policy-signed-interest.hpp
@@ -30,9 +30,7 @@
 #include <boost/multi_index/ordered_index.hpp>
 #include <boost/multi_index/sequenced_index.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Validation policy for signed Interests.
@@ -158,7 +156,7 @@
 
   void
   insertRecord(const Name& keyName,
-               std::optional<time::system_clock::TimePoint> timestamp,
+               std::optional<time::system_clock::time_point> timestamp,
                std::optional<uint64_t> seqNum,
                std::optional<SigNonce> nonce);
 
@@ -181,7 +179,7 @@
   struct LastInterestRecord
   {
     LastInterestRecord(const Name& keyName,
-                       std::optional<time::system_clock::TimePoint> timestamp,
+                       std::optional<time::system_clock::time_point> timestamp,
                        std::optional<uint64_t> seqNum)
       : keyName(keyName)
       , timestamp(timestamp)
@@ -191,10 +189,10 @@
     }
 
     Name keyName;
-    std::optional<time::system_clock::TimePoint> timestamp;
+    std::optional<time::system_clock::time_point> timestamp;
     std::optional<uint64_t> seqNum;
     NonceContainer observedNonces;
-    time::steady_clock::TimePoint lastRefreshed;
+    time::steady_clock::time_point lastRefreshed;
   };
 
   using Container = boost::multi_index_container<
@@ -204,7 +202,7 @@
         boost::multi_index::member<LastInterestRecord, Name, &LastInterestRecord::keyName>
       >,
       boost::multi_index::ordered_non_unique<
-        boost::multi_index::member<LastInterestRecord, time::steady_clock::TimePoint,
+        boost::multi_index::member<LastInterestRecord, time::steady_clock::time_point,
                                    &LastInterestRecord::lastRefreshed>
       >
     >
@@ -215,8 +213,6 @@
   Container::nth_index<1>::type& m_byLastRefreshed;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_POLICY_SIGNED_INTEREST_HPP
diff --git a/ndn-cxx/security/validation-policy-simple-hierarchy.cpp b/ndn-cxx/security/validation-policy-simple-hierarchy.cpp
index 6b5937f..15c06d6 100644
--- a/ndn-cxx/security/validation-policy-simple-hierarchy.cpp
+++ b/ndn-cxx/security/validation-policy-simple-hierarchy.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/security/validation-policy-simple-hierarchy.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 void
 ValidationPolicySimpleHierarchy::checkPolicy(const Data& data, const shared_ptr<ValidationState>& state,
@@ -83,6 +81,4 @@
   continueValidation(make_shared<CertificateRequest>(klName), state);
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validation-policy-simple-hierarchy.hpp b/ndn-cxx/security/validation-policy-simple-hierarchy.hpp
index aa0b593..0459ec1 100644
--- a/ndn-cxx/security/validation-policy-simple-hierarchy.hpp
+++ b/ndn-cxx/security/validation-policy-simple-hierarchy.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/validation-policy.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Validation policy for a simple hierarchical trust model
@@ -43,8 +41,6 @@
               const ValidationContinuation& continueValidation) override;
 };
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_POLICY_SIMPLE_HIERARCHY_HPP
diff --git a/ndn-cxx/security/validation-policy.cpp b/ndn-cxx/security/validation-policy.cpp
index 97a839b..d713e1e 100644
--- a/ndn-cxx/security/validation-policy.cpp
+++ b/ndn-cxx/security/validation-policy.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,9 +22,7 @@
 #include "ndn-cxx/security/validation-policy.hpp"
 #include "ndn-cxx/security/signing-info.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 void
 ValidationPolicy::setInnerPolicy(unique_ptr<ValidationPolicy> innerPolicy)
@@ -132,6 +130,4 @@
                               "` does not respect the naming conventions"));
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validation-policy.hpp b/ndn-cxx/security/validation-policy.hpp
index f49670a..8025bb5 100644
--- a/ndn-cxx/security/validation-policy.hpp
+++ b/ndn-cxx/security/validation-policy.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,7 @@
 #include "ndn-cxx/security/certificate-request.hpp"
 #include "ndn-cxx/security/validation-state.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Abstraction that implements a validation policy for Interest and Data packets.
@@ -179,8 +177,6 @@
 Name
 extractIdentityNameFromKeyLocator(const Name& keyLocator);
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_POLICY_HPP
diff --git a/ndn-cxx/security/validation-state.cpp b/ndn-cxx/security/validation-state.cpp
index 6fa2c96..cbb61d6 100644
--- a/ndn-cxx/security/validation-state.cpp
+++ b/ndn-cxx/security/validation-state.cpp
@@ -24,9 +24,7 @@
 #include "ndn-cxx/security/verification-helpers.hpp"
 #include "ndn-cxx/util/logger.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 NDN_LOG_INIT(ndn.security.ValidationState);
 
@@ -176,6 +174,4 @@
   m_outcome = false;
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validation-state.hpp b/ndn-cxx/security/validation-state.hpp
index de16915..3ce5f57 100644
--- a/ndn-cxx/security/validation-state.hpp
+++ b/ndn-cxx/security/validation-state.hpp
@@ -26,15 +26,13 @@
 #include "ndn-cxx/security/certificate.hpp"
 #include "ndn-cxx/security/signing-info.hpp"
 #include "ndn-cxx/security/validation-callback.hpp"
-#include "ndn-cxx/util/signal.hpp"
+#include "ndn-cxx/util/signal/signal.hpp"
 
 #include <list>
 #include <unordered_set>
 #include <boost/logic/tribool.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 class Validator;
 
@@ -239,7 +237,7 @@
   }
 
 public:
-  util::Signal<InterestValidationState, Interest> afterSuccess;
+  signal::Signal<InterestValidationState, Interest> afterSuccess;
 
 private:
   void
@@ -256,8 +254,6 @@
 
 using SignedInterestFormatTag = SimpleTag<SignedInterestFormat, 1002>;
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATION_STATE_HPP
diff --git a/ndn-cxx/security/validator-config.cpp b/ndn-cxx/security/validator-config.cpp
index cb19348..5cedf50 100644
--- a/ndn-cxx/security/validator-config.cpp
+++ b/ndn-cxx/security/validator-config.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,8 +22,7 @@
 #include "ndn-cxx/security/validator-config.hpp"
 #include "ndn-cxx/security/certificate-fetcher-from-network.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 ValidatorConfig::ValidatorConfig(std::unique_ptr<CertificateFetcher> fetcher,
                                  const CommandInterestOptions& ciOptions,
@@ -70,5 +69,4 @@
   m_policyConfig.load(configSection, filename);
 }
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validator-config/checker.cpp b/ndn-cxx/security/validator-config/checker.cpp
index c11b477..11f1da9 100644
--- a/ndn-cxx/security/validator-config/checker.cpp
+++ b/ndn-cxx/security/validator-config/checker.cpp
@@ -25,10 +25,7 @@
 
 #include <boost/algorithm/string/predicate.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
+namespace ndn::security::validator_config {
 
 Checker::Checker(tlv::SignatureTypeValue sigType)
   : m_sigType(sigType)
@@ -402,7 +399,4 @@
   }
 }
 
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::validator_config
diff --git a/ndn-cxx/security/validator-config/checker.hpp b/ndn-cxx/security/validator-config/checker.hpp
index 1156011..5e04e5e 100644
--- a/ndn-cxx/security/validator-config/checker.hpp
+++ b/ndn-cxx/security/validator-config/checker.hpp
@@ -27,9 +27,7 @@
 #include "ndn-cxx/security/validator-config/name-relation.hpp"
 #include "ndn-cxx/util/regex.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 class ValidationState;
 
@@ -185,8 +183,6 @@
 };
 
 } // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATOR_CONFIG_CHECKER_HPP
diff --git a/ndn-cxx/security/validator-config/common.hpp b/ndn-cxx/security/validator-config/common.hpp
index 93653ba..d4b1c9d 100644
--- a/ndn-cxx/security/validator-config/common.hpp
+++ b/ndn-cxx/security/validator-config/common.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,12 +28,9 @@
 
 #include <boost/property_tree/ptree.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
+namespace ndn::security::validator_config {
 
-typedef boost::property_tree::ptree ConfigSection;
+using ConfigSection = boost::property_tree::ptree;
 
 class Error : public std::runtime_error
 {
@@ -41,9 +38,6 @@
   using std::runtime_error::runtime_error;
 };
 
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::validator_config
 
 #endif // NDN_CXX_SECURITY_VALIDATOR_CONFIG_COMMON_HPP
diff --git a/ndn-cxx/security/validator-config/filter.cpp b/ndn-cxx/security/validator-config/filter.cpp
index 7421813..ea23f5e 100644
--- a/ndn-cxx/security/validator-config/filter.cpp
+++ b/ndn-cxx/security/validator-config/filter.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -29,10 +29,7 @@
 
 #include <boost/algorithm/string/predicate.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
+namespace ndn::security::validator_config {
 
 bool
 Filter::match(uint32_t pktType, const Name& pktName, const shared_ptr<ValidationState>& state)
@@ -156,7 +153,4 @@
   }
 }
 
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::validator_config
diff --git a/ndn-cxx/security/validator-config/filter.hpp b/ndn-cxx/security/validator-config/filter.hpp
index 41113f7..5c8286b 100644
--- a/ndn-cxx/security/validator-config/filter.hpp
+++ b/ndn-cxx/security/validator-config/filter.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,9 +28,7 @@
 #include "ndn-cxx/security/validator-config/name-relation.hpp"
 #include "ndn-cxx/util/regex.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 class ValidationState;
 
@@ -138,8 +136,6 @@
 };
 
 } // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATOR_CONFIG_FILTER_HPP
diff --git a/ndn-cxx/security/validator-config/name-relation.cpp b/ndn-cxx/security/validator-config/name-relation.cpp
index 05804d1..870b44e 100644
--- a/ndn-cxx/security/validator-config/name-relation.cpp
+++ b/ndn-cxx/security/validator-config/name-relation.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,7 @@
 
 #include <boost/algorithm/string/predicate.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
+namespace ndn::security::validator_config {
 
 std::ostream&
 operator<<(std::ostream& os, NameRelation relation)
@@ -73,7 +70,4 @@
   }
 }
 
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::validator_config
diff --git a/ndn-cxx/security/validator-config/name-relation.hpp b/ndn-cxx/security/validator-config/name-relation.hpp
index 8559770..97b842a 100644
--- a/ndn-cxx/security/validator-config/name-relation.hpp
+++ b/ndn-cxx/security/validator-config/name-relation.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,10 +25,7 @@
 #include "ndn-cxx/name.hpp"
 #include "ndn-cxx/security/validator-config/common.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
+namespace ndn::security::validator_config {
 
 enum class NameRelation {
   EQUAL,
@@ -52,9 +49,6 @@
 NameRelation
 getNameRelationFromString(const std::string& relationString);
 
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::validator_config
 
 #endif // NDN_CXX_SECURITY_VALIDATOR_CONFIG_NAME_RELATION_HPP
diff --git a/ndn-cxx/security/validator-config/rule.cpp b/ndn-cxx/security/validator-config/rule.cpp
index 3382e58..b60aa10 100644
--- a/ndn-cxx/security/validator-config/rule.cpp
+++ b/ndn-cxx/security/validator-config/rule.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,12 +25,9 @@
 
 #include <boost/algorithm/string/predicate.hpp>
 
-NDN_LOG_INIT(ndn.security.validator_config.Rule);
+namespace ndn::security::validator_config {
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
+NDN_LOG_INIT(ndn.security.validator_config.Rule);
 
 Rule::Rule(const std::string& id, uint32_t pktType)
   : m_id(id)
@@ -171,7 +168,4 @@
   return rule;
 }
 
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security::validator_config
diff --git a/ndn-cxx/security/validator-config/rule.hpp b/ndn-cxx/security/validator-config/rule.hpp
index e2d3daf..304d4d7 100644
--- a/ndn-cxx/security/validator-config/rule.hpp
+++ b/ndn-cxx/security/validator-config/rule.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 #include "ndn-cxx/security/validator-config/checker.hpp"
 #include "ndn-cxx/security/validator-config/filter.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 class ValidationState;
 
@@ -110,8 +108,6 @@
 };
 
 } // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATOR_CONFIG_RULE_HPP
diff --git a/ndn-cxx/security/validator-null.cpp b/ndn-cxx/security/validator-null.cpp
index 35c66cf..8e50065 100644
--- a/ndn-cxx/security/validator-null.cpp
+++ b/ndn-cxx/security/validator-null.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,7 @@
 #include "ndn-cxx/security/validation-policy-accept-all.hpp"
 #include "ndn-cxx/security/certificate-fetcher-offline.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 ValidatorNull::ValidatorNull()
   : Validator(make_unique<ValidationPolicyAcceptAll>(), make_unique<CertificateFetcherOffline>())
@@ -39,6 +37,4 @@
   return validator;
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validator-null.hpp b/ndn-cxx/security/validator-null.hpp
index 58fd1f8..fc14edf 100644
--- a/ndn-cxx/security/validator-null.hpp
+++ b/ndn-cxx/security/validator-null.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,7 @@
 
 #include "ndn-cxx/security/validator.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 /**
  * @brief Validator with "accept-all" policy and offline certificate fetcher
@@ -40,8 +38,6 @@
 Validator&
 getAcceptAllValidator();
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDATOR_NULL_HPP
diff --git a/ndn-cxx/security/validator.cpp b/ndn-cxx/security/validator.cpp
index fd9817f..ca829f9 100644
--- a/ndn-cxx/security/validator.cpp
+++ b/ndn-cxx/security/validator.cpp
@@ -24,9 +24,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
+namespace ndn::security {
 
 NDN_LOG_INIT(ndn.security.Validator);
 
@@ -198,6 +196,4 @@
   CertificateStorage::resetVerifiedCerts();
 }
 
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validator.hpp b/ndn-cxx/security/validator.hpp
index f08585d..d2f5fcb 100644
--- a/ndn-cxx/security/validator.hpp
+++ b/ndn-cxx/security/validator.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -34,7 +34,6 @@
 class Face;
 
 namespace security {
-inline namespace v2 {
 
 /**
  * @brief Interface for validating data and interest packets.
@@ -204,7 +203,6 @@
   size_t m_maxDepth{25};
 };
 
-} // inline namespace v2
 } // namespace security
 } // namespace ndn
 
diff --git a/ndn-cxx/security/validity-period.cpp b/ndn-cxx/security/validity-period.cpp
index c7f5b5d..1c911a8 100644
--- a/ndn-cxx/security/validity-period.cpp
+++ b/ndn-cxx/security/validity-period.cpp
@@ -22,8 +22,7 @@
 #include "ndn-cxx/security/validity-period.hpp"
 #include "ndn-cxx/encoding/block-helpers.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 using boost::chrono::time_point_cast;
 
@@ -33,21 +32,21 @@
 
 ValidityPeriod
 ValidityPeriod::makeRelative(time::seconds validFrom, time::seconds validUntil,
-                             const time::system_clock::TimePoint& now)
+                             const time::system_clock::time_point& now)
 {
   return ValidityPeriod(now + validFrom, now + validUntil);
 }
 
 ValidityPeriod::ValidityPeriod()
-  : ValidityPeriod(time::system_clock::TimePoint() + 1_ns,
-                   time::system_clock::TimePoint())
+  : ValidityPeriod(time::system_clock::time_point() + 1_ns,
+                   time::system_clock::time_point())
 {
 }
 
-ValidityPeriod::ValidityPeriod(const time::system_clock::TimePoint& notBefore,
-                               const time::system_clock::TimePoint& notAfter)
+ValidityPeriod::ValidityPeriod(const time::system_clock::time_point& notBefore,
+                               const time::system_clock::time_point& notAfter)
   : m_notBefore(time_point_cast<TimePoint::duration>(notBefore + TimePoint::duration(1) -
-                                                     time::system_clock::TimePoint::duration(1)))
+                                                     time::system_clock::time_point::duration(1)))
   , m_notAfter(time_point_cast<TimePoint::duration>(notAfter))
 {
 }
@@ -126,24 +125,24 @@
 }
 
 ValidityPeriod&
-ValidityPeriod::setPeriod(const time::system_clock::TimePoint& notBefore,
-                          const time::system_clock::TimePoint& notAfter)
+ValidityPeriod::setPeriod(const time::system_clock::time_point& notBefore,
+                          const time::system_clock::time_point& notAfter)
 {
   m_wire.reset();
   m_notBefore = time_point_cast<TimePoint::duration>(notBefore + TimePoint::duration(1) -
-                                                     time::system_clock::TimePoint::duration(1));
+                                                     time::system_clock::time_point::duration(1));
   m_notAfter = time_point_cast<TimePoint::duration>(notAfter);
   return *this;
 }
 
-std::pair<time::system_clock::TimePoint, time::system_clock::TimePoint>
+std::pair<time::system_clock::time_point, time::system_clock::time_point>
 ValidityPeriod::getPeriod() const
 {
   return {m_notBefore, m_notAfter};
 }
 
 bool
-ValidityPeriod::isValid(const time::system_clock::TimePoint& now) const
+ValidityPeriod::isValid(const time::system_clock::time_point& now) const
 {
   return m_notBefore <= now && now <= m_notAfter;
 }
@@ -156,5 +155,4 @@
   return os;
 }
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/validity-period.hpp b/ndn-cxx/security/validity-period.hpp
index 97bc47c..4a9f69e 100644
--- a/ndn-cxx/security/validity-period.hpp
+++ b/ndn-cxx/security/validity-period.hpp
@@ -26,8 +26,7 @@
 #include "ndn-cxx/encoding/tlv.hpp"
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 /**
  * @brief Represents a %ValidityPeriod TLV element.
@@ -52,7 +51,7 @@
    */
   static ValidityPeriod
   makeRelative(time::seconds validFrom, time::seconds validUntil,
-               const time::system_clock::TimePoint& now = time::system_clock::now());
+               const time::system_clock::time_point& now = time::system_clock::now());
 
   /** @brief Set validity period [UNIX epoch + 1 nanosecond, UNIX epoch] that is always invalid
    */
@@ -71,15 +70,15 @@
    *        - @p notBefore is rounded up the next whole second
    *        - @p notAfter is truncated to the previous whole second
    */
-  ValidityPeriod(const time::system_clock::TimePoint& notBefore,
-                 const time::system_clock::TimePoint& notAfter);
+  ValidityPeriod(const time::system_clock::time_point& notBefore,
+                 const time::system_clock::time_point& notAfter);
 
   /** @brief Check if @p now falls within the validity period
    *  @param now Time point to check if it falls within the period
    *  @return periodBegin <= @p now and @p now <= periodEnd
    */
   bool
-  isValid(const time::system_clock::TimePoint& now = time::system_clock::now()) const;
+  isValid(const time::system_clock::time_point& now = time::system_clock::now()) const;
 
   /** @brief Set validity period [@p notBefore, @p notAfter]
    *  @param notBefore exclusive beginning of the validity period range
@@ -90,12 +89,12 @@
    *        - @p notAfter is truncated to the previous whole second
    */
   ValidityPeriod&
-  setPeriod(const time::system_clock::TimePoint& notBefore,
-            const time::system_clock::TimePoint& notAfter);
+  setPeriod(const time::system_clock::time_point& notBefore,
+            const time::system_clock::time_point& notAfter);
 
   /** @brief Get the stored validity period
    */
-  std::pair<time::system_clock::TimePoint, time::system_clock::TimePoint>
+  std::pair<time::system_clock::time_point, time::system_clock::time_point>
   getPeriod() const;
 
   /** @brief Fast encoding or block size estimation
@@ -146,7 +145,6 @@
 std::ostream&
 operator<<(std::ostream& os, const ValidityPeriod& period);
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
 
 #endif // NDN_CXX_SECURITY_VALIDITY_PERIOD_HPP
diff --git a/ndn-cxx/security/verification-helpers.cpp b/ndn-cxx/security/verification-helpers.cpp
index 0a339f3..37fe838 100644
--- a/ndn-cxx/security/verification-helpers.cpp
+++ b/ndn-cxx/security/verification-helpers.cpp
@@ -36,8 +36,7 @@
 
 #include <openssl/crypto.h>
 
-namespace ndn {
-namespace security {
+namespace ndn::security {
 
 namespace {
 
@@ -261,5 +260,4 @@
   return verifySignature(parse(interest), tpm, keyName, digestAlgorithm);
 }
 
-} // namespace security
-} // namespace ndn
+} // namespace ndn::security
diff --git a/ndn-cxx/security/verification-helpers.hpp b/ndn-cxx/security/verification-helpers.hpp
index ee8c9ec..83ae137 100644
--- a/ndn-cxx/security/verification-helpers.hpp
+++ b/ndn-cxx/security/verification-helpers.hpp
@@ -44,9 +44,7 @@
 class PublicKey;
 } // namespace transform
 
-inline namespace v2 {
 class Certificate;
-} // inline namespace v2
 
 /**
  * @brief Verify @p blobs using @p key against @p sig.
diff --git a/ndn-cxx/transport/detail/stream-transport-impl.hpp b/ndn-cxx/transport/detail/stream-transport-impl.hpp
index 1b47f49..0ee1035 100644
--- a/ndn-cxx/transport/detail/stream-transport-impl.hpp
+++ b/ndn-cxx/transport/detail/stream-transport-impl.hpp
@@ -30,8 +30,7 @@
 #include <list>
 #include <queue>
 
-namespace ndn {
-namespace detail {
+namespace ndn::detail {
 
 /** \brief Implementation detail of a Boost.Asio-based stream-oriented transport.
  *  \tparam BaseTransport a subclass of Transport
@@ -241,7 +240,6 @@
   boost::asio::steady_timer m_connectTimer;
 };
 
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail
 
 #endif // NDN_CXX_TRANSPORT_DETAIL_STREAM_TRANSPORT_IMPL_HPP
diff --git a/ndn-cxx/transport/detail/stream-transport-with-resolver-impl.hpp b/ndn-cxx/transport/detail/stream-transport-with-resolver-impl.hpp
index 61c7d27..8d0de0c 100644
--- a/ndn-cxx/transport/detail/stream-transport-with-resolver-impl.hpp
+++ b/ndn-cxx/transport/detail/stream-transport-with-resolver-impl.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/transport/detail/stream-transport-impl.hpp"
 
-namespace ndn {
-namespace detail {
+namespace ndn::detail {
 
 /** \brief Implementation detail of a Boost.Asio-based stream-oriented transport
  *         with resolver support.
@@ -100,7 +99,6 @@
   }
 };
 
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::detail
 
 #endif // NDN_CXX_TRANSPORT_DETAIL_STREAM_TRANSPORT_WITH_RESOLVER_IMPL_HPP
diff --git a/ndn-cxx/util/dummy-client-face.cpp b/ndn-cxx/util/dummy-client-face.cpp
index 51fd77e..1f278e5 100644
--- a/ndn-cxx/util/dummy-client-face.cpp
+++ b/ndn-cxx/util/dummy-client-face.cpp
@@ -30,7 +30,6 @@
 #include <boost/asio/io_service.hpp>
 
 namespace ndn {
-namespace util {
 
 class DummyClientFace::Transport final : public ndn::Transport
 {
@@ -66,7 +65,7 @@
   }
 
 public:
-  Signal<Transport, Block> onSendBlock;
+  signal::Signal<Transport, Block> onSendBlock;
 };
 
 struct DummyClientFace::BroadcastLink
@@ -324,5 +323,4 @@
   }
 }
 
-} // namespace util
 } // namespace ndn
diff --git a/ndn-cxx/util/dummy-client-face.hpp b/ndn-cxx/util/dummy-client-face.hpp
index 22a80d8..62c0ba9 100644
--- a/ndn-cxx/util/dummy-client-face.hpp
+++ b/ndn-cxx/util/dummy-client-face.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,18 +23,19 @@
 #define NDN_CXX_UTIL_DUMMY_CLIENT_FACE_HPP
 
 #include "ndn-cxx/face.hpp"
-#include "ndn-cxx/util/signal.hpp"
 #include "ndn-cxx/security/key-chain.hpp"
+#include "ndn-cxx/util/signal/signal.hpp"
 
 namespace ndn {
-namespace util {
 
-/** \brief A client-side face for unit testing.
+/**
+ * \brief A client-side face for unit testing.
  */
-class DummyClientFace : public ndn::Face
+class DummyClientFace : public Face
 {
 public:
-  /** \brief %Options for DummyClientFace.
+  /**
+   * \brief %Options for DummyClientFace.
    */
   class Options
   {
@@ -176,19 +177,19 @@
    *
    *  After .expressInterest, .processEvents must be called before this signal would be emitted.
    */
-  Signal<DummyClientFace, Interest> onSendInterest;
+  signal::Signal<DummyClientFace, Interest> onSendInterest;
 
   /** \brief Emits whenever a Data packet is sent.
    *
    *  After .put, .processEvents must be called before this signal would be emitted.
    */
-  Signal<DummyClientFace, Data> onSendData;
+  signal::Signal<DummyClientFace, Data> onSendData;
 
   /** \brief Emits whenever a Nack is sent.
    *
    *  After .put, .processEvents must be called before this signal would be emitted.
    */
-  Signal<DummyClientFace, lp::Nack> onSendNack;
+  signal::Signal<DummyClientFace, lp::Nack> onSendNack;
 
 NDN_CXX_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   struct BroadcastLink;
@@ -198,7 +199,11 @@
   std::function<void(time::milliseconds)> m_processEventsOverride;
 };
 
+namespace util {
+/// \deprecated Use ndn::DummyClientFace
+using DummyClientFace = ::ndn::DummyClientFace;
 } // namespace util
+
 } // namespace ndn
 
 #endif // NDN_CXX_UTIL_DUMMY_CLIENT_FACE_HPP
diff --git a/ndn-cxx/util/exception.cpp b/ndn-cxx/util/exception.cpp
index d143692..684fc75 100644
--- a/ndn-cxx/util/exception.cpp
+++ b/ndn-cxx/util/exception.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include <sstream>
 
-namespace ndn {
-namespace exception {
+namespace ndn::exception {
 
 #ifdef NDN_CXX_HAVE_STACKTRACE
 std::string
@@ -41,5 +40,4 @@
 }
 #endif
 
-} // namespace exception
-} // namespace ndn
+} // namespace ndn::exception
diff --git a/ndn-cxx/util/exception.hpp b/ndn-cxx/util/exception.hpp
index a8cd326..dadb697 100644
--- a/ndn-cxx/util/exception.hpp
+++ b/ndn-cxx/util/exception.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -36,8 +36,7 @@
 #include <boost/stacktrace/stacktrace.hpp>
 #endif
 
-namespace ndn {
-namespace exception {
+namespace ndn::exception {
 
 #ifdef NDN_CXX_HAVE_STACKTRACE
 using errinfo_stacktrace = boost::error_info<struct stacktrace, boost::stacktrace::stacktrace>;
@@ -46,8 +45,7 @@
 to_string(const errinfo_stacktrace&);
 #endif
 
-} // namespace exception
-} // namespace ndn
+} // namespace ndn::exception
 
 /** \cond */
 #ifdef NDN_CXX_HAVE_STACKTRACE
diff --git a/ndn-cxx/util/impl/logger-android.cpp b/ndn-cxx/util/impl/logger-android.cpp
index bcfeef5..76aef0f 100644
--- a/ndn-cxx/util/impl/logger-android.cpp
+++ b/ndn-cxx/util/impl/logger-android.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,7 @@
 
 #include <android/log.h>
 
-namespace ndn {
-namespace util {
-namespace detail {
+namespace ndn::util::detail {
 
 class AndroidSinkBackend : public boost::log::sinks::basic_sink_backend<boost::log::sinks::concurrent_feeding>
 {
@@ -72,6 +70,4 @@
   return boost::make_shared<boost::log::sinks::synchronous_sink<AndroidSinkBackend>>();
 }
 
-} // namespace detail
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util::detail
diff --git a/ndn-cxx/util/impl/logger-android.hpp b/ndn-cxx/util/impl/logger-android.hpp
index e31402d..4a94e17 100644
--- a/ndn-cxx/util/impl/logger-android.hpp
+++ b/ndn-cxx/util/impl/logger-android.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,15 +28,11 @@
 #error "This file should not be compiled ..."
 #endif
 
-namespace ndn {
-namespace util {
-namespace detail {
+namespace ndn::util::detail {
 
 boost::shared_ptr<boost::log::sinks::sink>
 makeAndroidLogger();
 
-} // namespace detail
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util::detail
 
 #endif // NDN_CXX_UTIL_IMPL_LOGGER_ANDROID_HPP
diff --git a/ndn-cxx/util/impl/steady-timer.hpp b/ndn-cxx/util/impl/steady-timer.hpp
index d4219a0..75f374e 100644
--- a/ndn-cxx/util/impl/steady-timer.hpp
+++ b/ndn-cxx/util/impl/steady-timer.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include <boost/asio/basic_waitable_timer.hpp>
 #include <boost/asio/wait_traits.hpp>
 
-namespace boost {
-namespace asio {
+namespace boost::asio {
 
 template<>
 struct wait_traits<ndn::time::steady_clock>
@@ -40,12 +39,9 @@
   }
 };
 
-} // namespace asio
-} // namespace boost
+} // namespace boost::asio
 
-namespace ndn {
-namespace util {
-namespace detail {
+namespace ndn::detail {
 
 class SteadyTimer : public boost::asio::basic_waitable_timer<time::steady_clock>
 {
@@ -53,8 +49,6 @@
   using boost::asio::basic_waitable_timer<time::steady_clock>::basic_waitable_timer;
 };
 
-} // namespace detail
-} // namespace util
-} // namespace ndn
+} // namespace ndn::detail
 
 #endif // NDN_CXX_UTIL_IMPL_STEADY_TIMER_HPP
diff --git a/ndn-cxx/util/indented-stream.cpp b/ndn-cxx/util/indented-stream.cpp
index e178c13..00672db 100644
--- a/ndn-cxx/util/indented-stream.cpp
+++ b/ndn-cxx/util/indented-stream.cpp
@@ -27,8 +27,7 @@
 #include <boost/algorithm/string/split.hpp>
 #include <boost/algorithm/string/classification.hpp>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 IndentedStream::IndentedStream(std::ostream& os, std::string_view indent)
   : std::ostream(&m_buffer)
@@ -66,5 +65,4 @@
   return 0; // success
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
diff --git a/ndn-cxx/util/indented-stream.hpp b/ndn-cxx/util/indented-stream.hpp
index b2d5059..5bb0395 100644
--- a/ndn-cxx/util/indented-stream.hpp
+++ b/ndn-cxx/util/indented-stream.hpp
@@ -26,8 +26,7 @@
 #include <sstream>
 #include <string>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 /**
  * @brief Output to stream with specified indent or prefix
@@ -76,7 +75,6 @@
   StreamBuf m_buffer;
 };
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // NDN_CXX_UTIL_INDENTED_STREAM_HPP
diff --git a/ndn-cxx/util/io.cpp b/ndn-cxx/util/io.cpp
index 663c4e0..c40ebe9 100644
--- a/ndn-cxx/util/io.cpp
+++ b/ndn-cxx/util/io.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,8 +30,7 @@
 #include "ndn-cxx/security/transform/stream-source.hpp"
 #include "ndn-cxx/security/transform/strip-space.hpp"
 
-namespace ndn {
-namespace io {
+namespace ndn::io {
 
 shared_ptr<Buffer>
 loadBuffer(std::istream& is, IoEncoding encoding)
@@ -84,5 +83,4 @@
   NDN_THROW(std::invalid_argument("Unknown IoEncoding " + to_string(encoding)));
 }
 
-} // namespace io
-} // namespace ndn
+} // namespace ndn::io
diff --git a/ndn-cxx/util/io.hpp b/ndn-cxx/util/io.hpp
index 3500507..b439986 100644
--- a/ndn-cxx/util/io.hpp
+++ b/ndn-cxx/util/io.hpp
@@ -27,8 +27,7 @@
 
 #include <fstream>
 
-namespace ndn {
-namespace io {
+namespace ndn::io {
 
 class Error : public std::runtime_error
 {
@@ -201,7 +200,6 @@
   save(obj, os, encoding);
 }
 
-} // namespace io
-} // namespace ndn
+} // namespace ndn::io
 
 #endif // NDN_CXX_UTIL_IO_HPP
diff --git a/ndn-cxx/util/logger.cpp b/ndn-cxx/util/logger.cpp
index c9bea26..f2d3d07 100644
--- a/ndn-cxx/util/logger.cpp
+++ b/ndn-cxx/util/logger.cpp
@@ -22,8 +22,7 @@
 #include "ndn-cxx/util/logger.hpp"
 #include "ndn-cxx/util/logging.hpp"
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 std::ostream&
 operator<<(std::ostream& os, LogLevel level)
@@ -105,5 +104,4 @@
   Logging::get().registerLoggerNameImpl(name);
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
diff --git a/ndn-cxx/util/logger.hpp b/ndn-cxx/util/logger.hpp
index 3261b85..abee117 100644
--- a/ndn-cxx/util/logger.hpp
+++ b/ndn-cxx/util/logger.hpp
@@ -34,8 +34,7 @@
 
 #include <atomic>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 /**
  * \brief Indicates the severity level of a log message.
@@ -277,8 +276,7 @@
  */
 #define NDN_LOG_FATAL(expression) NDN_LOG_INTERNAL(FATAL, expression)
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // HAVE_NDN_CXX_CUSTOM_LOGGER
 
diff --git a/ndn-cxx/util/logging.cpp b/ndn-cxx/util/logging.cpp
index b6ffe7d..0dbdf81 100644
--- a/ndn-cxx/util/logging.cpp
+++ b/ndn-cxx/util/logging.cpp
@@ -42,8 +42,7 @@
 #include <iostream>
 #include <sstream>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 namespace log {
 
 static std::string
@@ -339,5 +338,4 @@
   }
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
diff --git a/ndn-cxx/util/logging.hpp b/ndn-cxx/util/logging.hpp
index 644bf77..169096a 100644
--- a/ndn-cxx/util/logging.hpp
+++ b/ndn-cxx/util/logging.hpp
@@ -33,8 +33,7 @@
 #include <set>
 #include <unordered_map>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 enum class LogLevel;
 class Logger;
@@ -221,8 +220,7 @@
   get().flushImpl();
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // HAVE_NDN_CXX_CUSTOM_LOGGER
 
diff --git a/ndn-cxx/util/notification-stream.hpp b/ndn-cxx/util/notification-stream.hpp
index de37498..dceba06 100644
--- a/ndn-cxx/util/notification-stream.hpp
+++ b/ndn-cxx/util/notification-stream.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include "ndn-cxx/security/key-chain.hpp"
 #include "ndn-cxx/util/concepts.hpp"
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 /** \brief Provides a publisher of Notification Stream.
  *  \sa https://redmine.named-data.net/projects/nfd/wiki/Notification
@@ -73,7 +72,6 @@
   uint64_t m_sequenceNo;
 };
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // NDN_CXX_UTIL_NOTIFICATION_STREAM_HPP
diff --git a/ndn-cxx/util/notification-subscriber.cpp b/ndn-cxx/util/notification-subscriber.cpp
index deaf8be..4a13240 100644
--- a/ndn-cxx/util/notification-subscriber.cpp
+++ b/ndn-cxx/util/notification-subscriber.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022 Regents of the University of California,
+ * Copyright (c) 2014-2023 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -30,8 +30,7 @@
 
 #include <cmath>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 NotificationSubscriberBase::NotificationSubscriberBase(Face& face, const Name& prefix,
                                                        time::milliseconds interestLifetime)
@@ -188,5 +187,4 @@
                                                                  random::generateWord32() % 100));
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
diff --git a/ndn-cxx/util/notification-subscriber.hpp b/ndn-cxx/util/notification-subscriber.hpp
index 3b78fdb..0191b7b 100644
--- a/ndn-cxx/util/notification-subscriber.hpp
+++ b/ndn-cxx/util/notification-subscriber.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022 Regents of the University of California,
+ * Copyright (c) 2014-2023 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -31,11 +31,10 @@
 #include "ndn-cxx/face.hpp"
 #include "ndn-cxx/util/concepts.hpp"
 #include "ndn-cxx/util/scheduler.hpp"
-#include "ndn-cxx/util/signal.hpp"
+#include "ndn-cxx/util/signal/signal.hpp"
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 class NotificationSubscriberBase : noncopyable
 {
@@ -120,15 +119,15 @@
 public:
   /** \brief Fires when a Nack is received.
    */
-  signal::Signal<NotificationSubscriberBase, lp::Nack> onNack;
+  Signal<NotificationSubscriberBase, lp::Nack> onNack;
 
   /** \brief Fires when no Notification is received within getInterestLifetime() period.
    */
-  signal::Signal<NotificationSubscriberBase> onTimeout;
+  Signal<NotificationSubscriberBase> onTimeout;
 
   /** \brief Fires when a Data packet in the Notification Stream cannot be decoded as Notification.
    */
-  signal::Signal<NotificationSubscriberBase, Data> onDecodeError;
+  Signal<NotificationSubscriberBase, Data> onDecodeError;
 
 private:
   Face& m_face;
@@ -168,7 +167,7 @@
   /** \brief Fires when a Notification is received.
    *  \note Removing all handlers will cause the subscriber to stop.
    */
-  signal::Signal<NotificationSubscriber, Notification> onNotification;
+  Signal<NotificationSubscriber, Notification> onNotification;
 
 private:
   bool
@@ -187,13 +186,11 @@
     catch (const tlv::Error&) {
       return false;
     }
-
     onNotification(notification);
     return true;
   }
 };
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // NDN_CXX_UTIL_NOTIFICATION_SUBSCRIBER_HPP
diff --git a/ndn-cxx/util/random.cpp b/ndn-cxx/util/random.cpp
index 0eec624..529fc69 100644
--- a/ndn-cxx/util/random.cpp
+++ b/ndn-cxx/util/random.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 #include <openssl/err.h>
 #include <openssl/rand.h>
 
-namespace ndn {
-namespace random {
+namespace ndn::random {
 
 uint32_t
 generateSecureWord32()
@@ -78,5 +77,4 @@
   return distribution(getRandomNumberEngine());
 }
 
-} // namespace random
-} // namespace ndn
+} // namespace ndn::random
diff --git a/ndn-cxx/util/random.hpp b/ndn-cxx/util/random.hpp
index be32ea1..cf03cc3 100644
--- a/ndn-cxx/util/random.hpp
+++ b/ndn-cxx/util/random.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 
 #include <random>
 
-namespace ndn {
-namespace random {
+namespace ndn::random {
 
 /**
  * @brief Generate a cryptographically secure random integer from the range [0, 2^32)
@@ -85,7 +84,6 @@
 uint64_t
 generateWord64();
 
-} // namespace random
-} // namespace ndn
+} // namespace ndn::random
 
 #endif // NDN_CXX_UTIL_RANDOM_HPP
diff --git a/ndn-cxx/util/rtt-estimator.cpp b/ndn-cxx/util/rtt-estimator.cpp
index 04310d2..3fb2cb5 100644
--- a/ndn-cxx/util/rtt-estimator.cpp
+++ b/ndn-cxx/util/rtt-estimator.cpp
@@ -26,8 +26,7 @@
 
 #include "ndn-cxx/util/rtt-estimator.hpp"
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 RttEstimator::RttEstimator(shared_ptr<const Options> options)
   : m_options(options ? std::move(options) : make_shared<const Options>())
@@ -81,5 +80,4 @@
   m_nRttSamples++;
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
diff --git a/ndn-cxx/util/rtt-estimator.hpp b/ndn-cxx/util/rtt-estimator.hpp
index ba3255c..355a314 100644
--- a/ndn-cxx/util/rtt-estimator.hpp
+++ b/ndn-cxx/util/rtt-estimator.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (C) 2016-2019, Arizona Board of Regents.
+ * Copyright (C) 2016-2023, Arizona Board of Regents.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -29,8 +29,7 @@
 
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 /**
  * @brief RTT/RTO estimator.
@@ -180,7 +179,6 @@
   int64_t m_nRttSamples = 0;
 };
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // NDN_CXX_UTIL_RTT_ESTIMATOR_HPP
diff --git a/ndn-cxx/util/scheduler.cpp b/ndn-cxx/util/scheduler.cpp
index b8a9691..ecc9c7f 100644
--- a/ndn-cxx/util/scheduler.cpp
+++ b/ndn-cxx/util/scheduler.cpp
@@ -23,8 +23,7 @@
 #include "ndn-cxx/util/impl/steady-timer.hpp"
 #include "ndn-cxx/util/scope.hpp"
 
-namespace ndn {
-namespace scheduler {
+namespace ndn::scheduler {
 
 /** \brief Stores internal information about a scheduled event
  */
@@ -46,7 +45,7 @@
 public:
   EventCallback callback;
   Scheduler::EventQueue::const_iterator queueIt;
-  time::steady_clock::TimePoint expireTime;
+  time::steady_clock::time_point expireTime;
   bool isExpired = false;
 };
 
@@ -82,7 +81,7 @@
 }
 
 Scheduler::Scheduler(boost::asio::io_service& ioService)
-  : m_timer(make_unique<util::detail::SteadyTimer>(ioService))
+  : m_timer(make_unique<detail::SteadyTimer>(ioService))
 {
 }
 
@@ -165,5 +164,4 @@
   }
 }
 
-} // namespace scheduler
-} // namespace ndn
+} // namespace ndn::scheduler
diff --git a/ndn-cxx/util/scheduler.hpp b/ndn-cxx/util/scheduler.hpp
index 547345a..b5dd908 100644
--- a/ndn-cxx/util/scheduler.hpp
+++ b/ndn-cxx/util/scheduler.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,11 +31,9 @@
 
 namespace ndn {
 
-namespace util {
 namespace detail {
 class SteadyTimer;
 } // namespace detail
-} // namespace util
 
 namespace scheduler {
 
@@ -178,7 +176,7 @@
   using EventQueue = std::multiset<shared_ptr<EventInfo>, EventQueueCompare>;
   EventQueue m_queue;
 
-  unique_ptr<util::detail::SteadyTimer> m_timer;
+  unique_ptr<detail::SteadyTimer> m_timer;
   bool m_isEventExecuting = false;
 
   friend EventId;
diff --git a/ndn-cxx/util/segment-fetcher.cpp b/ndn-cxx/util/segment-fetcher.cpp
index 727b836..b570a7b 100644
--- a/ndn-cxx/util/segment-fetcher.cpp
+++ b/ndn-cxx/util/segment-fetcher.cpp
@@ -35,7 +35,6 @@
 #include <cmath>
 
 namespace ndn {
-namespace util {
 
 void
 SegmentFetcher::Options::validate()
@@ -64,7 +63,7 @@
   , m_face(face)
   , m_scheduler(m_face.getIoService())
   , m_validator(validator)
-  , m_rttEstimator(make_shared<RttEstimator::Options>(options.rttOptions))
+  , m_rttEstimator(make_shared<util::RttEstimator::Options>(options.rttOptions))
   , m_timeLastSegmentReceived(time::steady_clock::now())
   , m_cwnd(options.initCwnd)
   , m_ssthresh(options.initSsthresh)
@@ -520,5 +519,4 @@
                   time::duration_cast<time::milliseconds>(m_rttEstimator.getEstimatedRto()));
 }
 
-} // namespace util
 } // namespace ndn
diff --git a/ndn-cxx/util/segment-fetcher.hpp b/ndn-cxx/util/segment-fetcher.hpp
index 9e7476b..202afff 100644
--- a/ndn-cxx/util/segment-fetcher.hpp
+++ b/ndn-cxx/util/segment-fetcher.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,13 +26,12 @@
 #include "ndn-cxx/security/validator.hpp"
 #include "ndn-cxx/util/rtt-estimator.hpp"
 #include "ndn-cxx/util/scheduler.hpp"
-#include "ndn-cxx/util/signal.hpp"
+#include "ndn-cxx/util/signal/signal.hpp"
 
 #include <queue>
 #include <set>
 
 namespace ndn {
-namespace util {
 
 /**
  * @brief Utility class to fetch the latest version of a segmented object.
@@ -72,9 +71,9 @@
  *
  * Example:
  * @code
- *   auto fetcher = SegmentFetcher::start(face, Interest("/data/prefix"), validator);
- *   fetcher->onComplete.connect([] (ConstBufferPtr data) {...});
- *   fetcher->onError.connect([] (uint32_t errorCode, const std::string& errorMsg) {...});
+ * auto fetcher = SegmentFetcher::start(face, Interest("/data/prefix"), validator);
+ * fetcher->onComplete.connect([] (ConstBufferPtr data) {...});
+ * fetcher->onError.connect([] (uint32_t errorCode, const std::string& errorMsg) {...});
  * @endcode
  */
 class SegmentFetcher : noncopyable
@@ -119,7 +118,7 @@
     double initSsthresh = std::numeric_limits<double>::max(); ///< initial slow start threshold
     double aiStep = 1.0; ///< additive increase step (in segments)
     double mdCoef = 0.5; ///< multiplicative decrease coefficient
-    RttEstimator::Options rttOptions; ///< options for RTT estimator
+    util::RttEstimator::Options rttOptions; ///< options for RTT estimator
     size_t flowControlWindow = 25000; ///< maximum number of segments stored in the reorder buffer
   };
 
@@ -232,46 +231,46 @@
    * @brief Emitted upon successful retrieval of the complete object (all segments).
    * @note Emitted only if SegmentFetcher is operating in 'block' mode.
    */
-  Signal<SegmentFetcher, ConstBufferPtr> onComplete;
+  signal::Signal<SegmentFetcher, ConstBufferPtr> onComplete;
 
   /**
    * @brief Emitted when the retrieval could not be completed due to an error.
    *
    * Handlers are provided with an error code and a string error message.
    */
-  Signal<SegmentFetcher, uint32_t, std::string> onError;
+  signal::Signal<SegmentFetcher, uint32_t, std::string> onError;
 
   /**
    * @brief Emitted whenever a data segment received.
    */
-  Signal<SegmentFetcher, Data> afterSegmentReceived;
+  signal::Signal<SegmentFetcher, Data> afterSegmentReceived;
 
   /**
    * @brief Emitted whenever a received data segment has been successfully validated.
    */
-  Signal<SegmentFetcher, Data> afterSegmentValidated;
+  signal::Signal<SegmentFetcher, Data> afterSegmentValidated;
 
   /**
    * @brief Emitted whenever an Interest for a data segment is nacked.
    */
-  Signal<SegmentFetcher> afterSegmentNacked;
+  signal::Signal<SegmentFetcher> afterSegmentNacked;
 
   /**
    * @brief Emitted whenever an Interest for a data segment times out.
    */
-  Signal<SegmentFetcher> afterSegmentTimedOut;
+  signal::Signal<SegmentFetcher> afterSegmentTimedOut;
 
   /**
    * @brief Emitted after each data segment in segment order has been validated.
    * @note Emitted only if SegmentFetcher is operating in 'in order' mode.
    */
-  Signal<SegmentFetcher, ConstBufferPtr> onInOrderData;
+  signal::Signal<SegmentFetcher, ConstBufferPtr> onInOrderData;
 
   /**
    * @brief Emitted on successful retrieval of all segments in 'in order' mode.
    * @note Emitted only if SegmentFetcher is operating in 'in order' mode.
    */
-  Signal<SegmentFetcher> onInOrderComplete;
+  signal::Signal<SegmentFetcher> onInOrderComplete;
 
 private:
   enum class SegmentState {
@@ -284,7 +283,7 @@
   {
   public:
     SegmentState state;
-    time::steady_clock::TimePoint sendTime;
+    time::steady_clock::time_point sendTime;
     ScopedPendingInterestHandle hdl;
     scheduler::ScopedEventId timeoutEvent;
   };
@@ -298,9 +297,9 @@
   Face& m_face;
   Scheduler m_scheduler;
   security::Validator& m_validator;
-  RttEstimator m_rttEstimator;
+  util::RttEstimator m_rttEstimator;
 
-  time::steady_clock::TimePoint m_timeLastSegmentReceived;
+  time::steady_clock::time_point m_timeLastSegmentReceived;
   std::queue<uint64_t> m_retxQueue;
   Name m_versionedDataName;
   uint64_t m_nextSegmentNum = 0;
@@ -320,7 +319,11 @@
   std::set<uint64_t> m_receivedSegments;
 };
 
+namespace util {
+/// \deprecated Use ndn::SegmentFetcher
+using SegmentFetcher = ::ndn::SegmentFetcher;
 } // namespace util
+
 } // namespace ndn
 
 #endif // NDN_CXX_UTIL_SEGMENT_FETCHER_HPP
diff --git a/ndn-cxx/util/segmenter.cpp b/ndn-cxx/util/segmenter.cpp
index 75962c0..fe6263e 100644
--- a/ndn-cxx/util/segmenter.cpp
+++ b/ndn-cxx/util/segmenter.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,7 +24,6 @@
 #include <boost/iostreams/read.hpp>
 
 namespace ndn {
-namespace util {
 
 Segmenter::Segmenter(KeyChain& keyChain, const security::SigningInfo& signingInfo)
   : m_keyChain(keyChain)
@@ -113,5 +112,4 @@
   return segments;
 }
 
-} // namespace util
 } // namespace ndn
diff --git a/ndn-cxx/util/segmenter.hpp b/ndn-cxx/util/segmenter.hpp
index 8ebd1aa..eb70985 100644
--- a/ndn-cxx/util/segmenter.hpp
+++ b/ndn-cxx/util/segmenter.hpp
@@ -26,7 +26,6 @@
 #include "ndn-cxx/util/span.hpp"
 
 namespace ndn {
-namespace util {
 
 /**
  * @brief Utility class to segment an object into multiple Data packets.
@@ -78,7 +77,11 @@
   security::SigningInfo m_signingInfo;
 };
 
+namespace util {
+/// \deprecated Use ndn::Segmenter
+using Segmenter = ::ndn::Segmenter;
 } // namespace util
+
 } // namespace ndn
 
 #endif // NDN_CXX_UTIL_SEGMENTER_HPP
diff --git a/ndn-cxx/util/sha256.cpp b/ndn-cxx/util/sha256.cpp
index 66355d6..47a02bb 100644
--- a/ndn-cxx/util/sha256.cpp
+++ b/ndn-cxx/util/sha256.cpp
@@ -27,8 +27,7 @@
 
 #include <openssl/crypto.h>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 Sha256::Sha256()
 {
@@ -146,5 +145,4 @@
   return os;
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
diff --git a/ndn-cxx/util/sha256.hpp b/ndn-cxx/util/sha256.hpp
index 2e7b09c..abf6919 100644
--- a/ndn-cxx/util/sha256.hpp
+++ b/ndn-cxx/util/sha256.hpp
@@ -25,8 +25,7 @@
 #include "ndn-cxx/encoding/buffer-stream.hpp"
 #include "ndn-cxx/security/transform/step-source.hpp"
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 /**
  * @brief Provides stateful SHA-256 digest calculation.
@@ -169,7 +168,6 @@
 std::ostream&
 operator<<(std::ostream& os, Sha256& digest);
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // NDN_CXX_UTIL_SHA256_HPP
diff --git a/ndn-cxx/util/signal/connection.cpp b/ndn-cxx/util/signal/connection.cpp
index 1cc3fa5..37c11fc 100644
--- a/ndn-cxx/util/signal/connection.cpp
+++ b/ndn-cxx/util/signal/connection.cpp
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/util/signal/connection.hpp"
 
-namespace ndn {
-namespace util {
-namespace signal {
+namespace ndn::signal {
 
 Connection::Connection(weak_ptr<DisconnectFunction> disconnect) noexcept
   : m_disconnect(std::move(disconnect))
@@ -39,6 +37,4 @@
   }
 }
 
-} // namespace signal
-} // namespace util
-} // namespace ndn
+} // namespace ndn::signal
diff --git a/ndn-cxx/util/signal/connection.hpp b/ndn-cxx/util/signal/connection.hpp
index 0952261..166b6cc 100644
--- a/ndn-cxx/util/signal/connection.hpp
+++ b/ndn-cxx/util/signal/connection.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,14 +24,13 @@
 
 #include "ndn-cxx/detail/common.hpp"
 
-namespace ndn {
-namespace util {
-namespace signal {
+namespace ndn::signal {
 
 using DisconnectFunction = std::function<void()>;
 
-/** \brief Represents a connection to a signal.
- *  \note This type is copyable. Any copy can be used to disconnect.
+/**
+ * \brief Represents a connection to a signal.
+ * \note This type is copyable. Any copy can be used to disconnect.
  */
 class Connection
 {
@@ -62,7 +61,7 @@
   explicit
   Connection(weak_ptr<DisconnectFunction> disconnect) noexcept;
 
-  template<typename Owner, typename ...TArgs>
+  template<typename Owner, typename... TArgs>
   friend class Signal;
 
 private:
@@ -99,8 +98,11 @@
   weak_ptr<DisconnectFunction> m_disconnect;
 };
 
-} // namespace signal
-} // namespace util
-} // namespace ndn
+} // namespace ndn::signal
+
+namespace ndn::util::signal {
+/// \deprecated Use ndn::signal::Connection
+using Connection = ::ndn::signal::Connection;
+} // namespace ndn::util::signal
 
 #endif // NDN_CXX_UTIL_SIGNAL_CONNECTION_HPP
diff --git a/ndn-cxx/util/signal/emit.hpp b/ndn-cxx/util/signal/emit.hpp
index a12aaaa..e1eb8d9 100644
--- a/ndn-cxx/util/signal/emit.hpp
+++ b/ndn-cxx/util/signal/emit.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -33,9 +33,7 @@
 #ifndef NDN_CXX_UTIL_SIGNAL_EMIT_HPP
 #define NDN_CXX_UTIL_SIGNAL_EMIT_HPP
 
-namespace ndn {
-namespace util {
-namespace signal {
+namespace ndn::signal {
 
 /** \brief (implementation detail) a filler for extra argument
  */
@@ -43,9 +41,7 @@
 {
 };
 
-} // namespace signal
-} // namespace util
-} // namespace ndn
+} // namespace ndn::signal
 
 /** \brief (implementation detail) declares a 'emit_signalName' method
  *  \note This macro should be used in 'protected' section so that it's accessible
@@ -57,7 +53,7 @@
  *        But only argument types that are compatible with Signal declaration will work.
  */
 #define DECLARE_SIGNAL_EMIT(signalName) \
-  template<typename ...TArgs> \
+  template<typename... TArgs> \
   void emit_##signalName(const TArgs&... args) \
   { \
     signalName(args...); \
@@ -74,6 +70,6 @@
 /** \brief (implementation detail)
  */
 #define emitSignal(...) \
-  NDN_CXX_SIGNAL_EMIT(__VA_ARGS__, ::ndn::util::signal::DummyExtraArg())
+  NDN_CXX_SIGNAL_EMIT(__VA_ARGS__, ::ndn::signal::DummyExtraArg())
 
 #endif // NDN_CXX_UTIL_SIGNAL_EMIT_HPP
diff --git a/ndn-cxx/util/signal/scoped-connection.cpp b/ndn-cxx/util/signal/scoped-connection.cpp
index 1a843b1..1aa59d7 100644
--- a/ndn-cxx/util/signal/scoped-connection.cpp
+++ b/ndn-cxx/util/signal/scoped-connection.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,9 +21,7 @@
 
 #include "ndn-cxx/util/signal/scoped-connection.hpp"
 
-namespace ndn {
-namespace util {
-namespace signal {
+namespace ndn::signal {
 
 ScopedConnection::ScopedConnection(Connection connection) noexcept
   : m_connection(std::move(connection))
@@ -63,6 +61,4 @@
   m_connection = {};
 }
 
-} // namespace signal
-} // namespace util
-} // namespace ndn
+} // namespace ndn::signal
diff --git a/ndn-cxx/util/signal/scoped-connection.hpp b/ndn-cxx/util/signal/scoped-connection.hpp
index 9ecf5e6..3f39e2e 100644
--- a/ndn-cxx/util/signal/scoped-connection.hpp
+++ b/ndn-cxx/util/signal/scoped-connection.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,11 +24,10 @@
 
 #include "ndn-cxx/util/signal/connection.hpp"
 
-namespace ndn {
-namespace util {
-namespace signal {
+namespace ndn::signal {
 
-/** \brief Disconnects a Connection automatically upon destruction.
+/**
+ * \brief Disconnects a Connection automatically upon destruction.
  */
 class ScopedConnection
 {
@@ -95,8 +94,11 @@
 inline ScopedConnection&
 ScopedConnection::operator=(ScopedConnection&&) noexcept = default;
 
-} // namespace signal
-} // namespace util
-} // namespace ndn
+} // namespace ndn::signal
+
+namespace ndn::util::signal {
+/// \deprecated Use ndn::signal::ScopedConnection
+using ScopedConnection = ::ndn::signal::ScopedConnection;
+} // namespace ndn::util::signal
 
 #endif // NDN_CXX_UTIL_SIGNAL_SCOPED_CONNECTION_HPP
diff --git a/ndn-cxx/util/signal/signal.hpp b/ndn-cxx/util/signal/signal.hpp
index a097f9c..79c1f27 100644
--- a/ndn-cxx/util/signal/signal.hpp
+++ b/ndn-cxx/util/signal/signal.hpp
@@ -27,9 +27,7 @@
 
 #include <list>
 
-namespace ndn {
-namespace util {
-namespace signal {
+namespace ndn::signal {
 
 class DummyExtraArg;
 
@@ -48,19 +46,22 @@
  *  \tparam TArgs types of signal arguments
  *  \sa signal-emit.hpp allows owner's derived classes to emit signals
  */
-template<typename Owner, typename ...TArgs>
+template<typename Owner, typename... TArgs>
 class Signal : noncopyable
 {
 public: // API for anyone
+#ifndef BOOST_ASSERT_IS_VOID
+  ~Signal() noexcept
+  {
+    BOOST_ASSERT(!m_isExecuting);
+  }
+#endif
+
   /**
    * \brief Represents a function that can connect to the signal.
    */
   using Handler = std::function<void(const TArgs&...)>;
 
-  Signal();
-
-  ~Signal();
-
   /** \brief Connects a handler to the signal.
    *  \note If invoked from a handler, the new handler won't receive the current emitted signal.
    *  \warning The handler is permitted to disconnect itself, but it must ensure its validity.
@@ -133,7 +134,7 @@
 
   /** \brief Is a signal handler executing?
    */
-  bool m_isExecuting;
+  bool m_isExecuting = false;
 
   /** \brief Iterator to current executing slot.
    *  \note This field is meaningful when isExecuting==true
@@ -146,19 +147,7 @@
   disconnect(typename SlotList::iterator it);
 };
 
-template<typename Owner, typename ...TArgs>
-Signal<Owner, TArgs...>::Signal()
-  : m_isExecuting(false)
-{
-}
-
-template<typename Owner, typename ...TArgs>
-Signal<Owner, TArgs...>::~Signal()
-{
-  BOOST_ASSERT(!m_isExecuting);
-}
-
-template<typename Owner, typename ...TArgs>
+template<typename Owner, typename... TArgs>
 Connection
 Signal<Owner, TArgs...>::connect(Handler handler)
 {
@@ -168,7 +157,7 @@
   return signal::Connection(it->disconnect);
 }
 
-template<typename Owner, typename ...TArgs>
+template<typename Owner, typename... TArgs>
 Connection
 Signal<Owner, TArgs...>::connectSingleShot(Handler handler)
 {
@@ -184,7 +173,7 @@
   return conn;
 }
 
-template<typename Owner, typename ...TArgs>
+template<typename Owner, typename... TArgs>
 void
 Signal<Owner, TArgs...>::disconnect(typename SlotList::iterator it)
 {
@@ -204,14 +193,14 @@
   }
 }
 
-template<typename Owner, typename ...TArgs>
+template<typename Owner, typename... TArgs>
 bool
 Signal<Owner, TArgs...>::isEmpty() const
 {
   return !m_isExecuting && m_slots.empty();
 }
 
-template<typename Owner, typename ...TArgs>
+template<typename Owner, typename... TArgs>
 void
 Signal<Owner, TArgs...>::operator()(const TArgs&... args)
 {
@@ -240,19 +229,19 @@
   }
 }
 
-template<typename Owner, typename ...TArgs>
+template<typename Owner, typename... TArgs>
 void
 Signal<Owner, TArgs...>::operator()(const TArgs&... args, const DummyExtraArg&)
 {
   this->operator()(args...);
 }
 
-} // namespace signal
+} // namespace ndn::signal
 
-// expose as ndn::util::Signal
-using signal::Signal;
-
-} // namespace util
-} // namespace ndn
+namespace ndn::util {
+/// \deprecated Use ndn::signal::Signal
+template<typename Owner, typename... TArgs>
+using Signal = ::ndn::signal::Signal<Owner, TArgs...>;
+} // namespace ndn::util
 
 #endif // NDN_CXX_UTIL_SIGNAL_SIGNAL_HPP
diff --git a/ndn-cxx/util/sqlite3-statement.cpp b/ndn-cxx/util/sqlite3-statement.cpp
index c7f7354..9b32f4c 100644
--- a/ndn-cxx/util/sqlite3-statement.cpp
+++ b/ndn-cxx/util/sqlite3-statement.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include <sqlite3.h>
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 Sqlite3Statement::~Sqlite3Statement()
 {
@@ -111,5 +110,4 @@
   return m_stmt;
 }
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
diff --git a/ndn-cxx/util/sqlite3-statement.hpp b/ndn-cxx/util/sqlite3-statement.hpp
index 4e7427a..c31909a 100644
--- a/ndn-cxx/util/sqlite3-statement.hpp
+++ b/ndn-cxx/util/sqlite3-statement.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 struct sqlite3;
 struct sqlite3_stmt;
 
-namespace ndn {
-namespace util {
+namespace ndn::util {
 
 /**
  * @brief Wrap an SQLite3 prepared statement.
@@ -151,7 +150,6 @@
   sqlite3_stmt* m_stmt;
 };
 
-} // namespace util
-} // namespace ndn
+} // namespace ndn::util
 
 #endif // NDN_CXX_UTIL_SQLITE3_STATEMENT_HPP
diff --git a/ndn-cxx/util/time-custom-clock.hpp b/ndn-cxx/util/time-custom-clock.hpp
index 99c5a61..db1e977 100644
--- a/ndn-cxx/util/time-custom-clock.hpp
+++ b/ndn-cxx/util/time-custom-clock.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace time {
+namespace ndn::time {
 
 /**
  * \brief Class implementing custom system or steady clock behavior
@@ -63,7 +62,6 @@
 setCustomClocks(shared_ptr<CustomSteadyClock> steadyClock = nullptr,
                 shared_ptr<CustomSystemClock> systemClock = nullptr);
 
-} // namespace time
-} // namespace ndn
+} // namespace ndn::time
 
 #endif // NDN_CXX_UTIL_TIME_CUSTOM_CLOCK_HPP
diff --git a/ndn-cxx/util/time-unit-test-clock.cpp b/ndn-cxx/util/time-unit-test-clock.cpp
index dd08f9f..6835499 100644
--- a/ndn-cxx/util/time-unit-test-clock.cpp
+++ b/ndn-cxx/util/time-unit-test-clock.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include <chrono>
 #include <thread>
 
-namespace ndn {
-namespace time {
+namespace ndn::time {
 
 template<class BaseClock, class ClockTraits>
 UnitTestClock<BaseClock, ClockTraits>::UnitTestClock(nanoseconds startTime)
@@ -97,5 +96,4 @@
 template
 class UnitTestClock<steady_clock>;
 
-} // namespace time
-} // namespace ndn
+} // namespace ndn::time
diff --git a/ndn-cxx/util/time-unit-test-clock.hpp b/ndn-cxx/util/time-unit-test-clock.hpp
index b148e63..2302677 100644
--- a/ndn-cxx/util/time-unit-test-clock.hpp
+++ b/ndn-cxx/util/time-unit-test-clock.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/util/time-custom-clock.hpp"
 
-namespace ndn {
-namespace time {
+namespace ndn::time {
 
 /**
  * @brief Traits for UnitTestClock, defining default behavior for different clocks
@@ -108,7 +107,6 @@
 using UnitTestSystemClock = UnitTestClock<system_clock>;
 using UnitTestSteadyClock = UnitTestClock<steady_clock>;
 
-} // namespace time
-} // namespace ndn
+} // namespace ndn::time
 
 #endif // NDN_CXX_UTIL_TIME_UNIT_TEST_CLOCK_HPP
diff --git a/ndn-cxx/util/time.cpp b/ndn-cxx/util/time.cpp
index e233ca5..ba9960a 100644
--- a/ndn-cxx/util/time.cpp
+++ b/ndn-cxx/util/time.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include <boost/date_time/posix_time/posix_time.hpp>
 #include <sstream>
 
-namespace ndn {
-namespace time {
+namespace ndn::time {
 
 static shared_ptr<CustomSystemClock> g_systemClock;
 static shared_ptr<CustomSteadyClock> g_steadyClock;
@@ -71,9 +70,9 @@
 #ifdef __APPLE__
 // Note that on macOS platform boost::steady_clock is not truly monotonic, so we use
 // system_clock instead.  Refer to https://svn.boost.org/trac/boost/ticket/7719)
-typedef boost::chrono::system_clock base_steady_clock;
+using base_steady_clock = boost::chrono::system_clock;
 #else
-typedef boost::chrono::steady_clock base_steady_clock;
+using base_steady_clock = boost::chrono::steady_clock;
 #endif
 
 steady_clock::time_point
@@ -207,11 +206,9 @@
   return convertToTimePoint(ptime);
 }
 
-} // namespace time
-} // namespace ndn
+} // namespace ndn::time
 
-namespace boost {
-namespace chrono {
+namespace boost::chrono {
 
 template<class CharT>
 std::basic_string<CharT>
@@ -242,5 +239,4 @@
 template struct clock_string<ndn::time::system_clock, char>;
 template struct clock_string<ndn::time::steady_clock, char>;
 
-} // namespace chrono
-} // namespace boost
+} // namespace boost::chrono
diff --git a/ndn-cxx/util/time.hpp b/ndn-cxx/util/time.hpp
index b4ffd53..be50c4b 100644
--- a/ndn-cxx/util/time.hpp
+++ b/ndn-cxx/util/time.hpp
@@ -33,9 +33,9 @@
 namespace time {
 
 template<typename Rep, typename Period>
-using duration = boost::chrono::duration<Rep, Period>;
+using duration = ::boost::chrono::duration<Rep, Period>;
 
-using boost::chrono::duration_cast;
+using ::boost::chrono::duration_cast;
 
 // C++20
 using days   = duration<int_fast32_t, boost::ratio<86400>>;
@@ -44,16 +44,17 @@
 using years  = duration<int_fast32_t, boost::ratio<31556952>>;
 
 // C++11
-using hours        = boost::chrono::hours;
-using minutes      = boost::chrono::minutes;
-using seconds      = boost::chrono::seconds;
-using milliseconds = boost::chrono::milliseconds;
-using microseconds = boost::chrono::microseconds;
-using nanoseconds  = boost::chrono::nanoseconds;
+using hours        = ::boost::chrono::hours;
+using minutes      = ::boost::chrono::minutes;
+using seconds      = ::boost::chrono::seconds;
+using milliseconds = ::boost::chrono::milliseconds;
+using microseconds = ::boost::chrono::microseconds;
+using nanoseconds  = ::boost::chrono::nanoseconds;
 
-/** \return The absolute value of the duration \p d.
- *  \note The function does not participate in the overload resolution
- *        unless std::numeric_limits<Rep>::is_signed is true.
+/**
+ * \brief Returns the absolute value of the duration \p d.
+ * \note This function does not participate in overload resolution
+ *       unless \c std::numeric_limits<Rep>::is_signed is true.
  */
 template<typename Rep, typename Period, typename = std::enable_if_t<std::numeric_limits<Rep>::is_signed>>
 constexpr duration<Rep, Period>
@@ -68,97 +69,97 @@
 inline namespace time_literals {
 
 constexpr time::days
-operator "" _day(unsigned long long days)
+operator ""_day(unsigned long long days)
 {
   return time::days{days};
 }
 
 constexpr time::duration<long double, time::days::period>
-operator "" _day(long double days)
+operator ""_day(long double days)
 {
   return time::duration<long double, time::days::period>{days};
 }
 
 constexpr time::days
-operator "" _days(unsigned long long days)
+operator ""_days(unsigned long long days)
 {
   return time::days{days};
 }
 
 constexpr time::duration<long double, time::days::period>
-operator "" _days(long double days)
+operator ""_days(long double days)
 {
   return time::duration<long double, time::days::period>{days};
 }
 
 constexpr time::hours
-operator "" _h(unsigned long long hrs)
+operator ""_h(unsigned long long hrs)
 {
   return time::hours{hrs};
 }
 
 constexpr time::duration<long double, time::hours::period>
-operator "" _h(long double hrs)
+operator ""_h(long double hrs)
 {
   return time::duration<long double, time::hours::period>{hrs};
 }
 
 constexpr time::minutes
-operator "" _min(unsigned long long mins)
+operator ""_min(unsigned long long mins)
 {
   return time::minutes{mins};
 }
 
 constexpr time::duration<long double, time::minutes::period>
-operator "" _min(long double mins)
+operator ""_min(long double mins)
 {
   return time::duration<long double, time::minutes::period>{mins};
 }
 
 constexpr time::seconds
-operator "" _s(unsigned long long secs)
+operator ""_s(unsigned long long secs)
 {
   return time::seconds{secs};
 }
 
 constexpr time::duration<long double, time::seconds::period>
-operator "" _s(long double secs)
+operator ""_s(long double secs)
 {
   return time::duration<long double, time::seconds::period>{secs};
 }
 
 constexpr time::milliseconds
-operator "" _ms(unsigned long long msecs)
+operator ""_ms(unsigned long long msecs)
 {
   return time::milliseconds{msecs};
 }
 
 constexpr time::duration<long double, time::milliseconds::period>
-operator "" _ms(long double msecs)
+operator ""_ms(long double msecs)
 {
   return time::duration<long double, time::milliseconds::period>{msecs};
 }
 
 constexpr time::microseconds
-operator "" _us(unsigned long long usecs)
+operator ""_us(unsigned long long usecs)
 {
   return time::microseconds{usecs};
 }
 
 constexpr time::duration<long double, time::microseconds::period>
-operator "" _us(long double usecs)
+operator ""_us(long double usecs)
 {
   return time::duration<long double, time::microseconds::period>{usecs};
 }
 
 constexpr time::nanoseconds
-operator "" _ns(unsigned long long nsecs)
+operator ""_ns(unsigned long long nsecs)
 {
   return time::nanoseconds{nsecs};
 }
 
 constexpr time::duration<long double, time::nanoseconds::period>
-operator "" _ns(long double nsecs)
+operator ""_ns(long double nsecs)
 {
   return time::duration<long double, time::nanoseconds::period>{nsecs};
 }
@@ -168,10 +169,10 @@
 
 namespace time {
 
-using namespace literals::time_literals;
+using namespace ::ndn::literals::time_literals;
 
 /**
- * \brief System clock
+ * \brief System clock.
  *
  * System clock represents the system-wide real time wall clock.
  *
@@ -181,28 +182,30 @@
  *
  * To get the current time:
  *
- * <code>
- *     const auto now = system_clock::now();
- * </code>
+ * \code
+ * const auto now = ndn::time::system_clock::now();
+ * \endcode
  *
  * To convert a time_point to/from UNIX timestamp:
  *
- * <code>
- *     system_clock::time_point time = ...;
- *     uint64_t timestampInMilliseconds = toUnixTimestamp(time).count();
- *     system_clock::time_point time2 = fromUnixTimestamp(milliseconds(timestampInMilliseconds));
- * </code>
+ * \code
+ * time::system_clock::time_point t1 = ...;
+ * auto timeInMilliseconds = time::toUnixTimestamp(t1).count();
+ * time::system_clock::time_point t2 = time::fromUnixTimestamp(time::milliseconds(timeInMilliseconds));
+ * \endcode
  */
 class system_clock
 {
 public:
-  using duration   = boost::chrono::system_clock::duration;
+  using duration   = ::boost::chrono::system_clock::duration;
   using rep        = duration::rep;
   using period     = duration::period;
-  using time_point = boost::chrono::time_point<system_clock>;
-  static constexpr bool is_steady = boost::chrono::system_clock::is_steady;
+  using time_point = ::boost::chrono::time_point<system_clock>;
+  static constexpr bool is_steady = ::boost::chrono::system_clock::is_steady;
 
+  /// \deprecated Use time_point
   using TimePoint = time_point;
+  /// \deprecated Use duration
   using Duration = duration;
 
   static time_point
@@ -216,7 +219,7 @@
 };
 
 /**
- * \brief Steady clock
+ * \brief Steady clock.
  *
  * Steady clock represents a monotonic clock. The time points of this
  * clock cannot decrease as physical time moves forward. This clock is
@@ -226,13 +229,15 @@
 class steady_clock
 {
 public:
-  using duration   = boost::chrono::steady_clock::duration;
+  using duration   = ::boost::chrono::steady_clock::duration;
   using rep        = duration::rep;
   using period     = duration::period;
-  using time_point = boost::chrono::time_point<steady_clock>;
+  using time_point = ::boost::chrono::time_point<steady_clock>;
   static constexpr bool is_steady = true;
 
+  /// \deprecated Use time_point
   using TimePoint = time_point;
+  /// \deprecated Use duration
   using Duration = duration;
 
   static time_point
@@ -353,8 +358,7 @@
 } // namespace time
 } // namespace ndn
 
-namespace boost {
-namespace chrono {
+namespace boost::chrono {
 
 template<typename CharT>
 struct clock_string<ndn::time::system_clock, CharT>
@@ -373,7 +377,6 @@
 extern template struct clock_string<ndn::time::system_clock, char>;
 extern template struct clock_string<ndn::time::steady_clock, char>;
 
-} // namespace chrono
-} // namespace boost
+} // namespace boost::chrono
 
 #endif // NDN_CXX_UTIL_TIME_HPP
diff --git a/tests/benchmarks/encoding-bench.cpp b/tests/benchmarks/encoding-bench.cpp
index 1adb452..a3e0b5e 100644
--- a/tests/benchmarks/encoding-bench.cpp
+++ b/tests/benchmarks/encoding-bench.cpp
@@ -30,11 +30,7 @@
 
 #include <iostream>
 
-namespace ndn {
-namespace tlv {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 template<size_t WIRE_SIZE>
 struct ReadVarNumberTest;
@@ -112,7 +108,7 @@
     uint64_t number = 0;
     for (int i = 0; i < N_ITERATIONS; ++i) {
       const uint8_t* begin2 = begin; // make a copy because readVarNumber increments the pointer
-      nOks += readVarNumber(begin2, end, number);
+      nOks += tlv::readVarNumber(begin2, end, number);
       nCorrects += number == Test::VALUE;
       // use the number and the return value, so compiler won't optimize out their computation
     }
@@ -124,6 +120,4 @@
             << " " << d << std::endl;
 }
 
-} // namespace tests
-} // namespace tlv
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/benchmarks/scheduler-bench.cpp b/tests/benchmarks/scheduler-bench.cpp
index 8897920..46af278 100644
--- a/tests/benchmarks/scheduler-bench.cpp
+++ b/tests/benchmarks/scheduler-bench.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,11 +28,7 @@
 #include <boost/asio/io_service.hpp>
 #include <iostream>
 
-namespace ndn {
-namespace scheduler {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_CASE(ScheduleCancel)
 {
@@ -40,7 +36,7 @@
   Scheduler sched(io);
 
   const size_t nEvents = 1000000;
-  std::vector<EventId> eventIds(nEvents);
+  std::vector<scheduler::EventId> eventIds(nEvents);
 
   auto d1 = timedExecute([&] {
     for (size_t i = 0; i < nEvents; ++i) {
@@ -67,8 +63,8 @@
   size_t nExpired = 0;
 
   // Events should expire at t1, but execution finishes at t2. The difference is the overhead.
-  time::steady_clock::TimePoint t1 = time::steady_clock::now() + 5_s;
-  time::steady_clock::TimePoint t2;
+  time::steady_clock::time_point t1 = time::steady_clock::now() + 5_s;
+  time::steady_clock::time_point t2;
   // +1ms ensures this extra event is executed last. In case the overhead is less than 1ms,
   // it will be reported as 1ms.
   sched.schedule(t1 - time::steady_clock::now() + 1_ms, [&] {
@@ -86,6 +82,4 @@
   std::cout << "execute " << nEvents << " events: " << (t2 - t1) << std::endl;
 }
 
-} // namespace tests
-} // namespace scheduler
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/benchmarks/timed-execute.hpp b/tests/benchmarks/timed-execute.hpp
index b33873d..7ce5a82 100644
--- a/tests/benchmarks/timed-execute.hpp
+++ b/tests/benchmarks/timed-execute.hpp
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/util/time.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 template<typename F>
 time::nanoseconds
@@ -37,7 +36,6 @@
   return after - before;
 }
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_BENCHMARKS_TIMED_EXECUTE_HPP
diff --git a/tests/integration/face.cpp b/tests/integration/face.cpp
index 9357094..7bd2408 100644
--- a/tests/integration/face.cpp
+++ b/tests/integration/face.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -37,8 +37,7 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 static Name
 makeVeryLongName(Name prefix = Name())
@@ -377,5 +376,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // IoRoutine
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/integration/network-monitor.cpp b/tests/integration/network-monitor.cpp
index 0e7be10..cf6d8bd 100644
--- a/tests/integration/network-monitor.cpp
+++ b/tests/integration/network-monitor.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -33,9 +33,9 @@
 #include <boost/asio/io_service.hpp>
 #include <iostream>
 
-namespace ndn {
-namespace net {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::net;
 
 static std::ostream&
 logEvent(const shared_ptr<const NetworkInterface>& ni = nullptr, std::ostream& os = std::cout)
@@ -66,7 +66,7 @@
 
   monitor.onInterfaceAdded.connect([] (const shared_ptr<const NetworkInterface>& ni) {
     logEvent(ni) << "onInterfaceAdded\n" << *ni;
-    logEvent(ni) << "link-type: " << detail::getLinkType(ni->getName()) << std::endl;
+    logEvent(ni) << "link-type: " << net::detail::getLinkType(ni->getName()) << std::endl;
 
     ni->onAddressAdded.connect([ni] (const NetworkAddress& address) {
       logEvent(ni) << "onAddressAdded " << address << std::endl;
@@ -78,7 +78,7 @@
 
     ni->onStateChanged.connect([ni] (InterfaceState oldState, InterfaceState newState) {
       logEvent(ni) << "onStateChanged " << oldState << " -> " << newState << std::endl;
-      logEvent(ni) << "link-type: " << detail::getLinkType(ni->getName()) << std::endl;
+      logEvent(ni) << "link-type: " << net::detail::getLinkType(ni->getName()) << std::endl;
     });
 
     ni->onMtuChanged.connect([ni] (uint32_t oldMtu, uint32_t newMtu) {
@@ -93,6 +93,4 @@
   io.run();
 }
 
-} // namespace tests
-} // namespace net
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/key-chain-fixture.cpp b/tests/key-chain-fixture.cpp
index 7bbcf6a..fefc7cf 100644
--- a/tests/key-chain-fixture.cpp
+++ b/tests/key-chain-fixture.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 
 #include <boost/filesystem/operations.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 using namespace ndn::security;
 
@@ -91,5 +90,4 @@
   return saveIdentityCert(id, filename);
 }
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/key-chain-fixture.hpp b/tests/key-chain-fixture.hpp
index ec1cac3..dc3a444 100644
--- a/tests/key-chain-fixture.hpp
+++ b/tests/key-chain-fixture.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 
 #include "tests/test-home-fixture.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * @brief A fixture providing an in-memory KeyChain.
@@ -81,7 +80,6 @@
   std::vector<std::string> m_certFiles;
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_KEY_CHAIN_FIXTURE_HPP
diff --git a/tests/test-common.cpp b/tests/test-common.cpp
index b0d06ea..e6c726e 100644
--- a/tests/test-common.cpp
+++ b/tests/test-common.cpp
@@ -21,8 +21,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 shared_ptr<Interest>
 makeInterest(const Name& name, bool canBePrefix, std::optional<time::milliseconds> lifetime,
@@ -61,5 +60,4 @@
   return nack;
 }
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/test-common.hpp b/tests/test-common.hpp
index 7b74f35..202fb18 100644
--- a/tests/test-common.hpp
+++ b/tests/test-common.hpp
@@ -27,8 +27,7 @@
 #include "ndn-cxx/lp/nack.hpp"
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * \brief Create an Interest
@@ -74,16 +73,15 @@
  * \param index the index of the name component to replace
  * \param args arguments to name::Component constructor
  */
-template<typename Packet, typename ...Args>
+template<typename Packet, typename... Args>
 void
-setNameComponent(Packet& pkt, ssize_t index, Args&& ...args)
+setNameComponent(Packet& pkt, ssize_t index, Args&&... args)
 {
   Name name = pkt.getName();
   name.set(index, name::Component(std::forward<Args>(args)...));
   pkt.setName(name);
 }
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_TEST_COMMON_HPP
diff --git a/tests/test-home-fixture.hpp b/tests/test-home-fixture.hpp
index 5778a6e..9801c92 100644
--- a/tests/test-home-fixture.hpp
+++ b/tests/test-home-fixture.hpp
@@ -32,8 +32,7 @@
 #include <boost/filesystem/operations.hpp>
 #include <boost/filesystem/path.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * @brief Fixture to adjust/restore NDN_CLIENT_PIB and NDN_CLIENT_TPM paths
@@ -121,7 +120,6 @@
   static constexpr std::string_view PATH{"build/keys"};
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_TEST_HOME_FIXTURE_HPP
diff --git a/tests/unit/clock-fixture.cpp b/tests/unit/clock-fixture.cpp
index 3f543ff..0efe19c 100644
--- a/tests/unit/clock-fixture.cpp
+++ b/tests/unit/clock-fixture.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -21,8 +21,7 @@
 
 #include "tests/unit/clock-fixture.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 ClockFixture::ClockFixture()
   : m_steadyClock(make_shared<time::UnitTestSteadyClock>())
@@ -52,5 +51,4 @@
   }
 }
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/clock-fixture.hpp b/tests/unit/clock-fixture.hpp
index 68dabbf..a0309ae 100644
--- a/tests/unit/clock-fixture.hpp
+++ b/tests/unit/clock-fixture.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/util/time-unit-test-clock.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 /** \brief A test fixture that overrides steady clock and system clock.
  */
@@ -79,7 +78,6 @@
   shared_ptr<time::UnitTestSystemClock> m_systemClock;
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_CLOCK_FIXTURE_HPP
diff --git a/tests/unit/data.t.cpp b/tests/unit/data.t.cpp
index 5706a3e..4672a83 100644
--- a/tests/unit/data.t.cpp
+++ b/tests/unit/data.t.cpp
@@ -34,8 +34,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<Data>));
 BOOST_CONCEPT_ASSERT((WireEncodable<Data>));
@@ -668,5 +667,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestData
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/detail/cancel-handle.t.cpp b/tests/unit/detail/cancel-handle.t.cpp
index 2e951dd..e35fe55 100644
--- a/tests/unit/detail/cancel-handle.t.cpp
+++ b/tests/unit/detail/cancel-handle.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2019 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace detail {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::detail::CancelHandle;
 
 BOOST_AUTO_TEST_SUITE(Detail)
 BOOST_AUTO_TEST_SUITE(TestCancelHandle)
@@ -55,7 +55,7 @@
 
 BOOST_AUTO_TEST_SUITE(ScopedHandle)
 
-using ScopedTestHandle = ScopedCancelHandle<CancelHandle>;
+using ScopedTestHandle = detail::ScopedCancelHandle<CancelHandle>;
 
 BOOST_AUTO_TEST_CASE(ManualCancel)
 {
@@ -134,6 +134,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCancelHandle
 BOOST_AUTO_TEST_SUITE_END() // Detail
 
-} // namespace tests
-} // namespace detail
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/detail/packet-base.t.cpp b/tests/unit/detail/packet-base.t.cpp
index 41d47db..32e7e42 100644
--- a/tests/unit/detail/packet-base.t.cpp
+++ b/tests/unit/detail/packet-base.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Detail)
 BOOST_AUTO_TEST_SUITE(TestPacketBase)
@@ -62,5 +61,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestPacketBase
 BOOST_AUTO_TEST_SUITE_END() // Detail
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/detail/tag-host.t.cpp b/tests/unit/detail/tag-host.t.cpp
index 72caa7e..c597203 100644
--- a/tests/unit/detail/tag-host.t.cpp
+++ b/tests/unit/detail/tag-host.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Detail)
 BOOST_AUTO_TEST_SUITE(TestTagHost)
@@ -53,7 +52,7 @@
   }
 };
 
-typedef boost::mpl::vector<TagHost, Interest, Data> Fixtures;
+using Fixtures = boost::mpl::vector<TagHost, Interest, Data>;
 
 BOOST_FIXTURE_TEST_CASE_TEMPLATE(Basic, T, Fixtures, T)
 {
@@ -84,5 +83,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestTagHost
 BOOST_AUTO_TEST_SUITE_END() // Detail
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/dummy-validator.hpp b/tests/unit/dummy-validator.hpp
index 63b7556..903fcea 100644
--- a/tests/unit/dummy-validator.hpp
+++ b/tests/unit/dummy-validator.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,8 +26,7 @@
 #include "ndn-cxx/security/validation-policy.hpp"
 #include "ndn-cxx/security/certificate-fetcher-offline.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * \brief A dummy validation policy for unit testing.
@@ -109,7 +108,6 @@
   }
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_DUMMY_VALIDATOR_HPP
diff --git a/tests/unit/encoding/block-helpers.t.cpp b/tests/unit/encoding/block-helpers.t.cpp
index ed8641e..18fce9a 100644
--- a/tests/unit/encoding/block-helpers.t.cpp
+++ b/tests/unit/encoding/block-helpers.t.cpp
@@ -24,9 +24,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace encoding {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::encoding;
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestBlockHelpers)
@@ -181,6 +181,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestBlockHelpers
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/encoding/block.t.cpp b/tests/unit/encoding/block.t.cpp
index 8dd21d3..c93a307 100644
--- a/tests/unit/encoding/block.t.cpp
+++ b/tests/unit/encoding/block.t.cpp
@@ -31,8 +31,7 @@
 #include <cstring>
 #include <sstream>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<Block>));
 
@@ -751,5 +750,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestBlock
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/encoding/buffer-stream.t.cpp b/tests/unit/encoding/buffer-stream.t.cpp
index 3f67d50..7442299 100644
--- a/tests/unit/encoding/buffer-stream.t.cpp
+++ b/tests/unit/encoding/buffer-stream.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestBufferStream)
@@ -84,5 +83,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestBufferStream
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/encoding/encoder.t.cpp b/tests/unit/encoding/encoder.t.cpp
index 0402f14..5e71e2c 100644
--- a/tests/unit/encoding/encoder.t.cpp
+++ b/tests/unit/encoding/encoder.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace encoding {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::encoding;
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestEncoder)
@@ -155,6 +155,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestEncoder
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/encoding/encoding-buffer.t.cpp b/tests/unit/encoding/encoding-buffer.t.cpp
index c0997b4..a5fa639 100644
--- a/tests/unit/encoding/encoding-buffer.t.cpp
+++ b/tests/unit/encoding/encoding-buffer.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,15 +24,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
-
-class BufferEstimatorFixture
-{
-public:
-  EncodingBuffer buffer;
-  EncodingEstimator estimator;
-};
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestEncodingBuffer)
@@ -61,6 +53,13 @@
   }
 }
 
+class BufferEstimatorFixture
+{
+public:
+  EncodingBuffer buffer;
+  EncodingEstimator estimator;
+};
+
 BOOST_FIXTURE_TEST_SUITE(PrependVarNumber, BufferEstimatorFixture)
 
 BOOST_AUTO_TEST_CASE(OneByte1)
@@ -198,5 +197,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestEncodingBuffer
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/encoding/estimator.t.cpp b/tests/unit/encoding/estimator.t.cpp
index cb86424..12a369b 100644
--- a/tests/unit/encoding/estimator.t.cpp
+++ b/tests/unit/encoding/estimator.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace encoding {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::encoding;
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestEstimator)
@@ -103,6 +103,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestEstimator
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace encoding
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/encoding/nfd-constants.t.cpp b/tests/unit/encoding/nfd-constants.t.cpp
index e1bc111..6821c44 100644
--- a/tests/unit/encoding/nfd-constants.t.cpp
+++ b/tests/unit/encoding/nfd-constants.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,9 @@
 #include <iomanip>
 #include <sstream>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestNfdConstants)
@@ -142,6 +142,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNfdConstants
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/encoding/tlv.t.cpp b/tests/unit/encoding/tlv.t.cpp
index 9cd7cc4..e38b5f2 100644
--- a/tests/unit/encoding/tlv.t.cpp
+++ b/tests/unit/encoding/tlv.t.cpp
@@ -34,9 +34,9 @@
 #include <boost/iostreams/device/array.hpp>
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace tlv {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::tlv;
 
 BOOST_AUTO_TEST_SUITE(Encoding)
 BOOST_AUTO_TEST_SUITE(TestTlv)
@@ -59,9 +59,9 @@
 using StreamIterator = std::istream_iterator<uint8_t>;
 
 #define ASSERT_READ_NUMBER_IS_FAST(T) \
-  static_assert(detail::IsContiguousIterator<T>, #T " is not fast")
+  static_assert(ndn::tlv::detail::IsContiguousIterator<T>, #T " is not fast")
 #define ASSERT_READ_NUMBER_IS_SLOW(T) \
-  static_assert(!detail::IsContiguousIterator<T>, #T " is not slow")
+  static_assert(!ndn::tlv::detail::IsContiguousIterator<T>, #T " is not slow")
 
 ASSERT_READ_NUMBER_IS_FAST(const uint8_t*);
 ASSERT_READ_NUMBER_IS_FAST(uint8_t*);
@@ -605,6 +605,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestTlv
 BOOST_AUTO_TEST_SUITE_END() // Encoding
 
-} // namespace tests
-} // namespace tlv
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/face.t.cpp b/tests/unit/face.t.cpp
index 9d622ed..c4ae026 100644
--- a/tests/unit/face.t.cpp
+++ b/tests/unit/face.t.cpp
@@ -31,10 +31,7 @@
 
 #include <boost/logic/tribool.hpp>
 
-namespace ndn {
-namespace tests {
-
-using ndn::util::DummyClientFace;
+namespace ndn::tests {
 
 struct WantPrefixRegReply;
 struct NoPrefixRegReply;
@@ -912,7 +909,7 @@
 {
 };
 
-typedef boost::mpl::vector<WithEnv, WithConfig> ConfigOptions;
+using ConfigOptions = boost::mpl::vector<WithEnv, WithConfig>;
 
 BOOST_FIXTURE_TEST_CASE(NoConfig, WithEnvAndConfig) // fixture configures test HOME and PIB/TPM path
 {
@@ -978,5 +975,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestFace
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage-fifo.t.cpp b/tests/unit/ims/in-memory-storage-fifo.t.cpp
index bdf86ea..632a566 100644
--- a/tests/unit/ims/in-memory-storage-fifo.t.cpp
+++ b/tests/unit/ims/in-memory-storage-fifo.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorageFifo)
@@ -90,5 +87,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorageFifo
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage-lfu.t.cpp b/tests/unit/ims/in-memory-storage-lfu.t.cpp
index 17aa9a6..34285dc 100644
--- a/tests/unit/ims/in-memory-storage-lfu.t.cpp
+++ b/tests/unit/ims/in-memory-storage-lfu.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorageLfu)
@@ -130,5 +127,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorageLfu
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage-lru.t.cpp b/tests/unit/ims/in-memory-storage-lru.t.cpp
index cbf2bab..5a37ca7 100644
--- a/tests/unit/ims/in-memory-storage-lru.t.cpp
+++ b/tests/unit/ims/in-memory-storage-lru.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorageLru)
@@ -132,5 +129,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorageLru
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage-persistent.t.cpp b/tests/unit/ims/in-memory-storage-persistent.t.cpp
index d0cabf9..33a3afb 100644
--- a/tests/unit/ims/in-memory-storage-persistent.t.cpp
+++ b/tests/unit/ims/in-memory-storage-persistent.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStoragePersistent)
@@ -78,5 +75,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStoragePersistent
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ims/in-memory-storage.t.cpp b/tests/unit/ims/in-memory-storage.t.cpp
index 27caa34..ac1c7c2 100644
--- a/tests/unit/ims/in-memory-storage.t.cpp
+++ b/tests/unit/ims/in-memory-storage.t.cpp
@@ -31,10 +31,7 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Ims)
 BOOST_AUTO_TEST_SUITE(TestInMemoryStorage)
@@ -601,5 +598,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInMemoryStorage
 BOOST_AUTO_TEST_SUITE_END() // Ims
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/interest-filter.t.cpp b/tests/unit/interest-filter.t.cpp
index 12aba0a..f4354e7 100644
--- a/tests/unit/interest-filter.t.cpp
+++ b/tests/unit/interest-filter.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,8 +26,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(TestInterestFilter)
 
@@ -52,7 +51,7 @@
 
 BOOST_AUTO_TEST_CASE(RegexConvertToName)
 {
-  util::DummyClientFace face;
+  DummyClientFace face;
   face.setInterestFilter(InterestFilter("/Hello/World", "<><b><c>?"),
     [] (const Name&, const Interest&) { BOOST_ERROR("unexpected Interest"); });
   face.processEvents(1_ms);
@@ -69,5 +68,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestInterestFilter
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/interest.t.cpp b/tests/unit/interest.t.cpp
index 73afe60..036dc72 100644
--- a/tests/unit/interest.t.cpp
+++ b/tests/unit/interest.t.cpp
@@ -24,8 +24,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((WireEncodable<Interest>));
 BOOST_CONCEPT_ASSERT((WireEncodableWithEncodingBuffer<Interest>));
@@ -1172,5 +1171,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestInterest
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/io-fixture.hpp b/tests/unit/io-fixture.hpp
index 1c872c4..4934954 100644
--- a/tests/unit/io-fixture.hpp
+++ b/tests/unit/io-fixture.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,8 +26,7 @@
 
 #include <boost/asio/io_service.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 class IoFixture : public ClockFixture
 {
@@ -49,7 +48,6 @@
   boost::asio::io_service m_io;
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_IO_FIXTURE_HPP
diff --git a/tests/unit/io-key-chain-fixture.hpp b/tests/unit/io-key-chain-fixture.hpp
index 2df51b1..3ac2edf 100644
--- a/tests/unit/io-key-chain-fixture.hpp
+++ b/tests/unit/io-key-chain-fixture.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,14 +25,12 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/unit/io-fixture.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 class IoKeyChainFixture : public IoFixture, public KeyChainFixture
 {
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_IO_KEY_CHAIN_FIXTURE_HPP
diff --git a/tests/unit/key-locator.t.cpp b/tests/unit/key-locator.t.cpp
index 7a8b636..50daa8c 100644
--- a/tests/unit/key-locator.t.cpp
+++ b/tests/unit/key-locator.t.cpp
@@ -26,8 +26,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<KeyLocator>));
 BOOST_CONCEPT_ASSERT((WireEncodable<KeyLocator>));
@@ -200,5 +199,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestKeyLocator
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/link.t.cpp b/tests/unit/link.t.cpp
index 106541a..f1bbd07 100644
--- a/tests/unit/link.t.cpp
+++ b/tests/unit/link.t.cpp
@@ -23,8 +23,7 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<Link>));
 BOOST_CONCEPT_ASSERT((WireEncodable<Link>));
@@ -175,5 +174,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestLink
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/lp/cache-policy.t.cpp b/tests/unit/lp/cache-policy.t.cpp
index 8b27a6c..08b9d25 100644
--- a/tests/unit/lp/cache-policy.t.cpp
+++ b/tests/unit/lp/cache-policy.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace lp {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::lp;
 
 BOOST_AUTO_TEST_SUITE(Lp)
 BOOST_AUTO_TEST_SUITE(TestCachePolicy)
@@ -92,6 +92,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCachePolicy
 BOOST_AUTO_TEST_SUITE_END() // Lp
 
-} // namespace tests
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/lp/fields.t.cpp b/tests/unit/lp/fields.t.cpp
index e828051..5028b2b 100644
--- a/tests/unit/lp/fields.t.cpp
+++ b/tests/unit/lp/fields.t.cpp
@@ -21,9 +21,9 @@
 
 #include "ndn-cxx/lp/fields.hpp"
 
-namespace ndn {
-namespace lp {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::lp;
 
 BOOST_CONCEPT_ASSERT((Field<FragmentField>));
 BOOST_CONCEPT_ASSERT((Field<SequenceField>));
@@ -40,6 +40,4 @@
 BOOST_CONCEPT_ASSERT((Field<NonDiscoveryField>));
 BOOST_CONCEPT_ASSERT((Field<PrefixAnnouncementField>));
 
-} // namespace tests
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/lp/nack-header.t.cpp b/tests/unit/lp/nack-header.t.cpp
index c914eb0..efe31b0 100644
--- a/tests/unit/lp/nack-header.t.cpp
+++ b/tests/unit/lp/nack-header.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace lp {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::lp;
 
 BOOST_AUTO_TEST_SUITE(Lp)
 BOOST_AUTO_TEST_SUITE(TestNackHeader)
@@ -112,6 +112,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNackHeader
 BOOST_AUTO_TEST_SUITE_END() // Lp
 
-} // namespace tests
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/lp/nack.t.cpp b/tests/unit/lp/nack.t.cpp
index ef30de1..64835ef 100644
--- a/tests/unit/lp/nack.t.cpp
+++ b/tests/unit/lp/nack.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace lp {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::lp;
 
 BOOST_AUTO_TEST_SUITE(Lp)
 BOOST_AUTO_TEST_SUITE(TestNack)
@@ -60,6 +60,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNack
 BOOST_AUTO_TEST_SUITE_END() // Lp
 
-} // namespace tests
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/lp/packet.t.cpp b/tests/unit/lp/packet.t.cpp
index 68f55fc..01cc05b 100644
--- a/tests/unit/lp/packet.t.cpp
+++ b/tests/unit/lp/packet.t.cpp
@@ -25,9 +25,9 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace lp {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::lp;
 
 BOOST_AUTO_TEST_SUITE(Lp)
 BOOST_AUTO_TEST_SUITE(TestPacket)
@@ -425,10 +425,10 @@
   BOOST_CHECK_THROW(packet.wireDecode(wire), Packet::Error);
 }
 
-BOOST_FIXTURE_TEST_CASE(DecodePrefixAnnouncement, ndn::tests::KeyChainFixture)
+BOOST_FIXTURE_TEST_CASE(DecodePrefixAnnouncement, KeyChainFixture)
 {
   // Construct Data which prefix announcement is attached to
-  auto data0 = ndn::tests::makeData("/edu/ua/cs/news/index.html");
+  auto data0 = makeData("/edu/ua/cs/news/index.html");
 
   Packet packet0;
   packet0.wireDecode(data0->wireEncode());
@@ -455,6 +455,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestPacket
 BOOST_AUTO_TEST_SUITE_END() // Lp
 
-} // namespace tests
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/lp/pit-token.t.cpp b/tests/unit/lp/pit-token.t.cpp
index 49d77c1..6f45b32 100644
--- a/tests/unit/lp/pit-token.t.cpp
+++ b/tests/unit/lp/pit-token.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace lp {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::lp;
 
 BOOST_AUTO_TEST_SUITE(Lp)
 BOOST_AUTO_TEST_SUITE(TestPitToken)
@@ -76,6 +76,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestPitToken
 BOOST_AUTO_TEST_SUITE_END() // Lp
 
-} // namespace tests
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/lp/prefix-announcement-header.t.cpp b/tests/unit/lp/prefix-announcement-header.t.cpp
index a107eb5..ef4b11f 100644
--- a/tests/unit/lp/prefix-announcement-header.t.cpp
+++ b/tests/unit/lp/prefix-announcement-header.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,12 +25,12 @@
 #include "tests/boost-test.hpp"
 #include "tests/key-chain-fixture.hpp"
 
-namespace ndn {
-namespace lp {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::lp;
 
 BOOST_AUTO_TEST_SUITE(Lp)
-BOOST_FIXTURE_TEST_SUITE(TestPrefixAnnouncementHeader, ndn::tests::KeyChainFixture)
+BOOST_FIXTURE_TEST_SUITE(TestPrefixAnnouncementHeader, KeyChainFixture)
 
 BOOST_AUTO_TEST_CASE(EncodeDecode)
 {
@@ -45,7 +45,7 @@
   const Data& data = pa.toData(m_keyChain, signingWithSha256(), 1);
   Block encodedData = data.wireEncode();
 
-  Block expectedBlock(tlv::PrefixAnnouncement);
+  Block expectedBlock(ndn::lp::tlv::PrefixAnnouncement);
   expectedBlock.push_back(encodedData);
   expectedBlock.encode();
 
@@ -64,6 +64,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestPrefixAnnouncementHeader
 BOOST_AUTO_TEST_SUITE_END() // Lp
 
-} // namespace tests
-} // namespace lp
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/meta-info.t.cpp b/tests/unit/meta-info.t.cpp
index f909565..2e37ea5 100644
--- a/tests/unit/meta-info.t.cpp
+++ b/tests/unit/meta-info.t.cpp
@@ -23,8 +23,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((WireEncodable<MetaInfo>));
 BOOST_CONCEPT_ASSERT((WireEncodableWithEncodingBuffer<MetaInfo>));
@@ -161,5 +160,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestMetaInfo
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/metadata-object.t.cpp b/tests/unit/metadata-object.t.cpp
index 3fd5d09..480f7d4 100644
--- a/tests/unit/metadata-object.t.cpp
+++ b/tests/unit/metadata-object.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 #include "tests/boost-test.hpp"
 #include "tests/key-chain-fixture.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 class MetadataObjectFixture : public KeyChainFixture
 {
@@ -167,5 +166,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestMetadataObject
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/control-response.t.cpp b/tests/unit/mgmt/control-response.t.cpp
index 1dd69b1..7e72c26 100644
--- a/tests/unit/mgmt/control-response.t.cpp
+++ b/tests/unit/mgmt/control-response.t.cpp
@@ -24,9 +24,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace mgmt {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::mgmt;
 
 BOOST_CONCEPT_ASSERT((WireEncodable<ControlResponse>));
 BOOST_CONCEPT_ASSERT((WireDecodable<ControlResponse>));
@@ -62,6 +62,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestControlResponse
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/dispatcher.t.cpp b/tests/unit/mgmt/dispatcher.t.cpp
index 9b01628..1e1c947 100644
--- a/tests/unit/mgmt/dispatcher.t.cpp
+++ b/tests/unit/mgmt/dispatcher.t.cpp
@@ -26,11 +26,9 @@
 #include "tests/test-common.hpp"
 #include "tests/unit/io-key-chain-fixture.hpp"
 
-namespace ndn {
-namespace mgmt {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::mgmt;
 
 class DispatcherFixture : public IoKeyChainFixture
 {
@@ -43,7 +41,7 @@
   }
 
 public:
-  util::DummyClientFace face;
+  DummyClientFace face;
   mgmt::Dispatcher dispatcher;
   InMemoryStorageFifo& storage;
 };
@@ -473,6 +471,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestDispatcher
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/channel-status.t.cpp b/tests/unit/mgmt/nfd/channel-status.t.cpp
index 8036d0d..b9c6455 100644
--- a/tests/unit/mgmt/nfd/channel-status.t.cpp
+++ b/tests/unit/mgmt/nfd/channel-status.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<ChannelStatus>));
 
@@ -85,6 +85,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/command-options.t.cpp b/tests/unit/mgmt/nfd/command-options.t.cpp
index d41c512..f7d74b1 100644
--- a/tests/unit/mgmt/nfd/command-options.t.cpp
+++ b/tests/unit/mgmt/nfd/command-options.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_AUTO_TEST_SUITE(Mgmt)
 BOOST_AUTO_TEST_SUITE(Nfd)
@@ -74,6 +74,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/control-command.t.cpp b/tests/unit/mgmt/nfd/control-command.t.cpp
index 25371fd..2da5270 100644
--- a/tests/unit/mgmt/nfd/control-command.t.cpp
+++ b/tests/unit/mgmt/nfd/control-command.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_AUTO_TEST_SUITE(Mgmt)
 BOOST_AUTO_TEST_SUITE(Nfd)
@@ -500,6 +500,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/control-parameters.t.cpp b/tests/unit/mgmt/nfd/control-parameters.t.cpp
index 4866620..e89b4f3 100644
--- a/tests/unit/mgmt/nfd/control-parameters.t.cpp
+++ b/tests/unit/mgmt/nfd/control-parameters.t.cpp
@@ -24,9 +24,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((WireEncodable<ControlParameters>));
 BOOST_CONCEPT_ASSERT((WireDecodable<ControlParameters>));
@@ -248,6 +248,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/controller-fixture.hpp b/tests/unit/mgmt/nfd/controller-fixture.hpp
index 38b44fd..d1cd401 100644
--- a/tests/unit/mgmt/nfd/controller-fixture.hpp
+++ b/tests/unit/mgmt/nfd/controller-fixture.hpp
@@ -28,11 +28,7 @@
 #include "tests/unit/dummy-validator.hpp"
 #include "tests/unit/io-key-chain-fixture.hpp"
 
-namespace ndn {
-namespace nfd {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 class ControllerFixture : public IoKeyChainFixture
 {
@@ -59,16 +55,14 @@
   }
 
 protected:
-  ndn::util::DummyClientFace face;
+  DummyClientFace face;
   DummyValidator m_validator;
-  Controller controller;
-  CommandFailureCallback commandFailCallback;
-  DatasetFailureCallback datasetFailCallback;
+  nfd::Controller controller;
+  nfd::CommandFailureCallback commandFailCallback;
+  nfd::DatasetFailureCallback datasetFailCallback;
   std::vector<uint32_t> failCodes;
 };
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_MGMT_NFD_CONTROLLER_FIXTURE_HPP
diff --git a/tests/unit/mgmt/nfd/controller.t.cpp b/tests/unit/mgmt/nfd/controller.t.cpp
index d68611f..6760d5e 100644
--- a/tests/unit/mgmt/nfd/controller.t.cpp
+++ b/tests/unit/mgmt/nfd/controller.t.cpp
@@ -25,11 +25,9 @@
 #include "tests/test-common.hpp"
 #include "tests/unit/mgmt/nfd/controller-fixture.hpp"
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::nfd;
 
 BOOST_AUTO_TEST_SUITE(Mgmt)
 BOOST_AUTO_TEST_SUITE(Nfd)
@@ -260,6 +258,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/cs-info.t.cpp b/tests/unit/mgmt/nfd/cs-info.t.cpp
index 70d8a20..9e4a437 100644
--- a/tests/unit/mgmt/nfd/cs-info.t.cpp
+++ b/tests/unit/mgmt/nfd/cs-info.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<CsInfo>));
 
@@ -126,6 +126,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/face-event-notification.t.cpp b/tests/unit/mgmt/nfd/face-event-notification.t.cpp
index 97b3000..3686b17 100644
--- a/tests/unit/mgmt/nfd/face-event-notification.t.cpp
+++ b/tests/unit/mgmt/nfd/face-event-notification.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((NotificationStreamItem<FaceEventNotification>));
 
@@ -268,6 +268,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/face-query-filter.t.cpp b/tests/unit/mgmt/nfd/face-query-filter.t.cpp
index 1f83f82..1234259 100644
--- a/tests/unit/mgmt/nfd/face-query-filter.t.cpp
+++ b/tests/unit/mgmt/nfd/face-query-filter.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<FaceQueryFilter>));
 BOOST_CONCEPT_ASSERT((WireEncodable<FaceQueryFilter>));
@@ -146,6 +146,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/face-status.t.cpp b/tests/unit/mgmt/nfd/face-status.t.cpp
index 275acf2..24be329 100644
--- a/tests/unit/mgmt/nfd/face-status.t.cpp
+++ b/tests/unit/mgmt/nfd/face-status.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<FaceStatus>));
 
@@ -178,6 +178,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/fib-entry.t.cpp b/tests/unit/mgmt/nfd/fib-entry.t.cpp
index 81f94e5..d802250 100644
--- a/tests/unit/mgmt/nfd/fib-entry.t.cpp
+++ b/tests/unit/mgmt/nfd/fib-entry.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<NextHopRecord>));
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<FibEntry>));
@@ -212,6 +212,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/forwarder-status.t.cpp b/tests/unit/mgmt/nfd/forwarder-status.t.cpp
index 6492e55..056917d 100644
--- a/tests/unit/mgmt/nfd/forwarder-status.t.cpp
+++ b/tests/unit/mgmt/nfd/forwarder-status.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<ForwarderStatus>));
 
@@ -140,6 +140,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/rib-entry.t.cpp b/tests/unit/mgmt/nfd/rib-entry.t.cpp
index 3479c01..ae924bf 100644
--- a/tests/unit/mgmt/nfd/rib-entry.t.cpp
+++ b/tests/unit/mgmt/nfd/rib-entry.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<Route>));
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<RibEntry>));
@@ -240,6 +240,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/status-dataset.t.cpp b/tests/unit/mgmt/nfd/status-dataset.t.cpp
index 511498d..bb6acad 100644
--- a/tests/unit/mgmt/nfd/status-dataset.t.cpp
+++ b/tests/unit/mgmt/nfd/status-dataset.t.cpp
@@ -25,11 +25,9 @@
 #include "tests/test-common.hpp"
 #include "tests/unit/mgmt/nfd/controller-fixture.hpp"
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::nfd;
 
 BOOST_AUTO_TEST_SUITE(Mgmt)
 BOOST_AUTO_TEST_SUITE(Nfd)
@@ -479,6 +477,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/nfd/strategy-choice.t.cpp b/tests/unit/mgmt/nfd/strategy-choice.t.cpp
index 92f271c..63d644b 100644
--- a/tests/unit/mgmt/nfd/strategy-choice.t.cpp
+++ b/tests/unit/mgmt/nfd/strategy-choice.t.cpp
@@ -26,9 +26,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace nfd {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::nfd;
 
 BOOST_CONCEPT_ASSERT((StatusDatasetItem<StrategyChoice>));
 
@@ -95,6 +95,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Nfd
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace nfd
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/mgmt/status-dataset-context.t.cpp b/tests/unit/mgmt/status-dataset-context.t.cpp
index 69b2694..f219729 100644
--- a/tests/unit/mgmt/status-dataset-context.t.cpp
+++ b/tests/unit/mgmt/status-dataset-context.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,11 +23,9 @@
 
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace mgmt {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::mgmt;
 
 class StatusDatasetContextFixture
 {
@@ -301,6 +299,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestStatusDatasetContext
 BOOST_AUTO_TEST_SUITE_END() // Mgmt
 
-} // namespace tests
-} // namespace mgmt
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/name-component.t.cpp b/tests/unit/name-component.t.cpp
index a35f980..d72de0f 100644
--- a/tests/unit/name-component.t.cpp
+++ b/tests/unit/name-component.t.cpp
@@ -30,9 +30,10 @@
 #include <boost/lexical_cast.hpp>
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace name {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::name::Component;
+using ndn::name::UriFormat;
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<Component>));
 BOOST_CONCEPT_ASSERT((WireEncodable<Component>));
@@ -616,6 +617,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestNameComponent
 
-} // namespace tests
-} // namespace name
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/name.t.cpp b/tests/unit/name.t.cpp
index 2e107f5..da95aed 100644
--- a/tests/unit/name.t.cpp
+++ b/tests/unit/name.t.cpp
@@ -26,11 +26,9 @@
 #include <unordered_map>
 #include <boost/range/concepts.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
-using Component = name::Component;
-using UriFormat = name::UriFormat;
+using ndn::name::Component;
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<Name>));
 BOOST_CONCEPT_ASSERT((WireEncodable<Name>));
@@ -61,7 +59,7 @@
   BOOST_CHECK_EQUAL(name[4], Component("\x1C\x9F"));
   BOOST_CHECK(name[5].isImplicitSha256Digest());
 
-  BOOST_CHECK_EQUAL(name.toUri(UriFormat::CANONICAL),
+  BOOST_CHECK_EQUAL(name.toUri(name::UriFormat::CANONICAL),
                     "/8=Emid/25042=P3/8=.../8=..../8=%1C%9F/"
                     "1=%04%15%E3bJ%15%18P%AChl%84%F1U%F2%98%08%C0%DDs%81%9A%A4%A4%C2%0B%E7%3AM%8A%87L");
 
@@ -349,7 +347,7 @@
   BOOST_TEST(number == 25912);
 
   const auto tp = time::system_clock::now();
-  time::system_clock::TimePoint tp2;
+  time::system_clock::time_point tp2;
   BOOST_CHECK_NO_THROW(tp2 = name.appendTimestamp(tp).at(-1).toTimestamp());
   BOOST_TEST(time::abs(tp2 - tp) <= 1_us);
 
@@ -561,5 +559,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestName
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/ndebug.t.cpp b/tests/unit/ndebug.t.cpp
index 39dcd8f..4fe1347 100644
--- a/tests/unit/ndebug.t.cpp
+++ b/tests/unit/ndebug.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(TestNdebug)
 
@@ -51,5 +50,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestNdebug
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/net/dns.t.cpp b/tests/unit/net/dns.t.cpp
index b6a24b5..ac734dd 100644
--- a/tests/unit/net/dns.t.cpp
+++ b/tests/unit/net/dns.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,10 +26,9 @@
 
 #include <boost/asio/io_service.hpp>
 
-namespace ndn {
-namespace dns {
-namespace tests {
+namespace ndn::tests {
 
+using namespace ndn::dns;
 using boost::asio::ip::address_v4;
 using boost::asio::ip::address_v6;
 
@@ -169,6 +168,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestDns
 BOOST_AUTO_TEST_SUITE_END() // Net
 
-} // namespace tests
-} // namespace dns
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/net/ethernet.t.cpp b/tests/unit/net/ethernet.t.cpp
index 162170b..0fc5357 100644
--- a/tests/unit/net/ethernet.t.cpp
+++ b/tests/unit/net/ethernet.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018 Regents of the University of California,
+ * Copyright (c) 2014-2023 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -29,8 +29,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Net)
 BOOST_AUTO_TEST_SUITE(TestEthernet)
@@ -113,5 +112,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestEthernet
 BOOST_AUTO_TEST_SUITE_END() // Net
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/net/face-uri.t.cpp b/tests/unit/net/face-uri.t.cpp
index d21d70f..34e050e 100644
--- a/tests/unit/net/face-uri.t.cpp
+++ b/tests/unit/net/face-uri.t.cpp
@@ -34,8 +34,7 @@
 
 #include <boost/concept_check.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<FaceUri>));
 
@@ -614,5 +613,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestFaceUri
 BOOST_AUTO_TEST_SUITE_END() // Net
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/net/network-configuration-detector.cpp b/tests/unit/net/network-configuration-detector.cpp
index 84e1244..f8a8816 100644
--- a/tests/unit/net/network-configuration-detector.cpp
+++ b/tests/unit/net/network-configuration-detector.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,35 +27,30 @@
 #include <boost/asio/ip/udp.hpp>
 #include <boost/range/iterator_range_core.hpp>
 
-namespace ndn {
-namespace tests {
-
-bool NetworkConfigurationDetector::m_isInitialized = false;
-bool NetworkConfigurationDetector::m_hasIpv4 = false;
-bool NetworkConfigurationDetector::m_hasIpv6 = false;
+namespace ndn::tests {
 
 bool
 NetworkConfigurationDetector::hasIpv4()
 {
-  if (!m_isInitialized) {
+  if (!s_isInitialized) {
     detect();
   }
-  return m_hasIpv4;
+  return s_hasIpv4;
 }
 
 bool
 NetworkConfigurationDetector::hasIpv6()
 {
-  if (!m_isInitialized) {
+  if (!s_isInitialized) {
     detect();
   }
-  return m_hasIpv6;
+  return s_hasIpv6;
 }
 
 void
 NetworkConfigurationDetector::detect()
 {
-  typedef boost::asio::ip::basic_resolver<boost::asio::ip::udp> BoostResolver;
+  using BoostResolver = boost::asio::ip::basic_resolver<boost::asio::ip::udp>;
 
   boost::asio::io_service ioService;
   BoostResolver resolver(ioService);
@@ -66,22 +61,21 @@
   boost::system::error_code errorCode;
   BoostResolver::iterator begin = resolver.resolve(query, errorCode);
   if (errorCode) {
-    m_isInitialized = true;
+    s_isInitialized = true;
     return;
   }
   BoostResolver::iterator end;
 
   for (const auto& i : boost::make_iterator_range(begin, end)) {
     if (i.endpoint().address().is_v4()) {
-      m_hasIpv4 = true;
+      s_hasIpv4 = true;
     }
     else if (i.endpoint().address().is_v6()) {
-      m_hasIpv6 = true;
+      s_hasIpv6 = true;
     }
   }
 
-  m_isInitialized = true;
+  s_isInitialized = true;
 }
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/net/network-configuration-detector.hpp b/tests/unit/net/network-configuration-detector.hpp
index 5c0c34b..7264e68 100644
--- a/tests/unit/net/network-configuration-detector.hpp
+++ b/tests/unit/net/network-configuration-detector.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -47,8 +47,7 @@
     } \
   } while (false)
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 class NetworkConfigurationDetector
 {
@@ -64,12 +63,11 @@
   detect();
 
 private:
-  static bool m_isInitialized;
-  static bool m_hasIpv4;
-  static bool m_hasIpv6;
+  static inline bool s_isInitialized = false;
+  static inline bool s_hasIpv4 = false;
+  static inline bool s_hasIpv6 = false;
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_NET_NETWORK_CONFIGURATION_DETECTOR_HPP
diff --git a/tests/unit/net/network-monitor-stub.t.cpp b/tests/unit/net/network-monitor-stub.t.cpp
index 453a510..0ef8a9d 100644
--- a/tests/unit/net/network-monitor-stub.t.cpp
+++ b/tests/unit/net/network-monitor-stub.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace net {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::net;
 
 BOOST_AUTO_TEST_SUITE(Net)
 BOOST_AUTO_TEST_SUITE(TestNetworkMonitorStub)
@@ -120,6 +120,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNetworkMonitorStub
 BOOST_AUTO_TEST_SUITE_END() // Net
 
-} // namespace tests
-} // namespace net
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/net/network-monitor.t.cpp b/tests/unit/net/network-monitor.t.cpp
index 132d0db..4515258 100644
--- a/tests/unit/net/network-monitor.t.cpp
+++ b/tests/unit/net/network-monitor.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,9 @@
 
 #include <boost/asio/io_service.hpp>
 
-namespace ndn {
-namespace net {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::net;
 
 BOOST_AUTO_TEST_SUITE(Net)
 BOOST_AUTO_TEST_SUITE(TestNetworkMonitor)
@@ -69,6 +69,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNetworkMonitor
 BOOST_AUTO_TEST_SUITE_END() // Net
 
-} // namespace tests
-} // namespace net
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/prefix-announcement.t.cpp b/tests/unit/prefix-announcement.t.cpp
index 9a3eba9..a13e9f5 100644
--- a/tests/unit/prefix-announcement.t.cpp
+++ b/tests/unit/prefix-announcement.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/test-common.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(TestPrefixAnnouncement)
 
@@ -265,5 +264,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestPrefixAnnouncement
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/additional-description.t.cpp b/tests/unit/security/additional-description.t.cpp
index 82dd606..af71ce4 100644
--- a/tests/unit/security/additional-description.t.cpp
+++ b/tests/unit/security/additional-description.t.cpp
@@ -24,9 +24,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::security::AdditionalDescription;
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<AdditionalDescription>));
 BOOST_CONCEPT_ASSERT((WireEncodable<AdditionalDescription>));
@@ -99,6 +99,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestAdditionalDescription
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/certificate-bundle-fetcher.t.cpp b/tests/unit/security/certificate-bundle-fetcher.t.cpp
index 0c300b7..1c7b8b8 100644
--- a/tests/unit/security/certificate-bundle-fetcher.t.cpp
+++ b/tests/unit/security/certificate-bundle-fetcher.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,12 +26,9 @@
 #include "tests/test-common.hpp"
 #include "tests/unit/security/validator-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestCertificateBundleFetcher)
@@ -45,21 +42,10 @@
   }
 };
 
-class BundleWithFinalBlockId
-{
-};
-
-class BundleWithoutFinalBlockId
-{
-};
-
-class Timeout
-{
-};
-
-class Nack
-{
-};
+struct BundleWithFinalBlockId {};
+struct BundleWithoutFinalBlockId {};
+struct Timeout {};
+struct Nack {};
 
 template<class Response>
 class CertificateBundleFetcherFixture : public HierarchicalValidatorFixture<ValidationPolicySimpleHierarchy,
@@ -198,7 +184,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCertificateBundleFetcher
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/certificate-cache.t.cpp b/tests/unit/security/certificate-cache.t.cpp
index 51aa72b..acbdd00 100644
--- a/tests/unit/security/certificate-cache.t.cpp
+++ b/tests/unit/security/certificate-cache.t.cpp
@@ -25,12 +25,7 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/unit/clock-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 class CertificateCacheFixture : public ClockFixture, public KeyChainFixture
 {
@@ -60,7 +55,7 @@
   }
 
 public:
-  CertificateCache certCache;
+  security::CertificateCache certCache;
   Identity identity;
   Certificate cert;
 };
@@ -104,7 +99,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCertificateCache
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/certificate-fetcher-direct-fetch.t.cpp b/tests/unit/security/certificate-fetcher-direct-fetch.t.cpp
index 7c9ba90..a843ca6 100644
--- a/tests/unit/security/certificate-fetcher-direct-fetch.t.cpp
+++ b/tests/unit/security/certificate-fetcher-direct-fetch.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,27 +30,16 @@
 #include <boost/range/adaptor/sliced.hpp>
 #include <boost/range/adaptor/strided.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestCertificateFetcherDirectFetch)
 
-class Cert
-{
-};
-
-class Timeout
-{
-};
-
-class Nack
-{
-};
+struct Cert {};
+struct Timeout {};
+struct Nack {};
 
 template<class Response>
 class CertificateFetcherDirectFetchFixture : public HierarchicalValidatorFixture<ValidationPolicySimpleHierarchy,
@@ -260,7 +249,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCertificateFetcherDirectFetch
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/certificate-fetcher-from-network.t.cpp b/tests/unit/security/certificate-fetcher-from-network.t.cpp
index cb3e0b5..7ffc276 100644
--- a/tests/unit/security/certificate-fetcher-from-network.t.cpp
+++ b/tests/unit/security/certificate-fetcher-from-network.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,27 +27,16 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/validator-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestCertificateFetcherFromNetwork)
 
-class Cert
-{
-};
-
-class Timeout
-{
-};
-
-class Nack
-{
-};
+struct Cert {};
+struct Timeout {};
+struct Nack {};
 
 template<class Response>
 class CertificateFetcherFromNetworkFixture : public HierarchicalValidatorFixture<ValidationPolicySimpleHierarchy,
@@ -135,7 +124,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCertificateFetcherFromNetwork
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/certificate-fetcher-offline.t.cpp b/tests/unit/security/certificate-fetcher-offline.t.cpp
index f48971f..147701f 100644
--- a/tests/unit/security/certificate-fetcher-offline.t.cpp
+++ b/tests/unit/security/certificate-fetcher-offline.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,10 +25,9 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/validator-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 
@@ -66,7 +65,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCertificateFetcherOffline
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/certificate.t.cpp b/tests/unit/security/certificate.t.cpp
index 44ae731..facb261 100644
--- a/tests/unit/security/certificate.t.cpp
+++ b/tests/unit/security/certificate.t.cpp
@@ -30,12 +30,10 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using ndn::security::Certificate;
+using ndn::security::ValidityPeriod;
 
 BOOST_CONCEPT_ASSERT((WireEncodable<Certificate>));
 BOOST_CONCEPT_ASSERT((WireDecodable<Certificate>));
@@ -379,6 +377,9 @@
 
 BOOST_AUTO_TEST_CASE(Helpers)
 {
+  using ndn::security::extractIdentityFromCertName;
+  using ndn::security::extractKeyNameFromCertName;
+
   BOOST_CHECK_EQUAL(extractIdentityFromCertName("/KEY/hello/world/v=1"), "/");
   BOOST_CHECK_EQUAL(extractIdentityFromCertName("/hello/world/KEY/!/self/v=42"), "/hello/world");
 
@@ -399,7 +400,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCertificate
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/detail/certificate-bundle-decoder.t.cpp b/tests/unit/security/detail/certificate-bundle-decoder.t.cpp
index a9fe998..3cb3eb7 100644
--- a/tests/unit/security/detail/certificate-bundle-decoder.t.cpp
+++ b/tests/unit/security/detail/certificate-bundle-decoder.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,12 +24,9 @@
 #include "tests/boost-test.hpp"
 #include "tests/key-chain-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace detail {
-namespace tests {
+namespace ndn::tests {
 
-class CertificateBundleDecoderFixture : public ndn::tests::KeyChainFixture
+class CertificateBundleDecoderFixture : public KeyChainFixture
 {
 protected:
   CertificateBundleDecoderFixture()
@@ -51,7 +48,7 @@
   }
 
 protected:
-  CertificateBundleDecoder cbd;
+  security::detail::CertificateBundleDecoder cbd;
   Block certBlock1;
   Block certBlock2;
   size_t nCertsCompleted = 0;
@@ -213,7 +210,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestCertificateBundleEncoderDecoder
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace detail
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/interest-signer.t.cpp b/tests/unit/security/interest-signer.t.cpp
index b4a3991..b44546b 100644
--- a/tests/unit/security/interest-signer.t.cpp
+++ b/tests/unit/security/interest-signer.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,11 +25,10 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/unit/clock-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using ndn::security::InterestSigner;
+using ndn::security::SigningInfo;
 
 class InterestSignerFixture : public ClockFixture, public KeyChainFixture
 {
@@ -123,6 +122,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestInterestSigner
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/key-chain.t.cpp b/tests/unit/security/key-chain.t.cpp
index be544a4..d0b717f 100644
--- a/tests/unit/security/key-chain.t.cpp
+++ b/tests/unit/security/key-chain.t.cpp
@@ -31,12 +31,9 @@
 #include <openssl/opensslv.h>
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_FIXTURE_TEST_SUITE(TestKeyChain, TestHomeEnvSaver)
@@ -800,7 +797,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestKeyChain
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/key-params.t.cpp b/tests/unit/security/key-params.t.cpp
index f051b06..27f098a 100644
--- a/tests/unit/security/key-params.t.cpp
+++ b/tests/unit/security/key-params.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestKeyParams)
@@ -162,5 +161,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestKeyParams
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/certificate-container.t.cpp b/tests/unit/security/pib/certificate-container.t.cpp
index b1d4343..ecfd0b9 100644
--- a/tests/unit/security/pib/certificate-container.t.cpp
+++ b/tests/unit/security/pib/certificate-container.t.cpp
@@ -26,15 +26,13 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 NDN_CXX_ASSERT_FORWARD_ITERATOR(CertificateContainer::const_iterator);
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 BOOST_FIXTURE_TEST_SUITE(TestCertificateContainer, PibDataFixture)
 
 BOOST_AUTO_TEST_CASE(AddGetRemove)
@@ -72,7 +70,7 @@
     BOOST_CHECK_EQUAL(cert1, id1Key1Cert1);
     BOOST_CHECK_EQUAL(cert2, id1Key1Cert2);
     Name id1Key1Cert3Name = Name(id1Key1Name).append("issuer").appendVersion(3);
-    BOOST_CHECK_THROW(container.get(id1Key1Cert3Name), pib::Pib::Error);
+    BOOST_CHECK_THROW(container.get(id1Key1Cert3Name), Pib::Error);
   }
 
   {
@@ -158,10 +156,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestCertificateContainer
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/identity-container.t.cpp b/tests/unit/security/pib/identity-container.t.cpp
index ea97da0..81f9ad0 100644
--- a/tests/unit/security/pib/identity-container.t.cpp
+++ b/tests/unit/security/pib/identity-container.t.cpp
@@ -26,15 +26,13 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 NDN_CXX_ASSERT_FORWARD_ITERATOR(IdentityContainer::const_iterator);
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 BOOST_FIXTURE_TEST_SUITE(TestIdentityContainer, PibDataFixture)
 
 BOOST_AUTO_TEST_CASE(AddGetRemove)
@@ -74,7 +72,7 @@
     Identity identity2 = container.get(id2);
     BOOST_CHECK_EQUAL(identity1.getName(), id1);
     BOOST_CHECK_EQUAL(identity2.getName(), id2);
-    BOOST_CHECK_THROW(container.get(Name("/non-existing")), pib::Pib::Error);
+    BOOST_CHECK_THROW(container.get(Name("/non-existing")), Pib::Error);
   }
 
   {
@@ -150,10 +148,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestIdentityContainer
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/identity.t.cpp b/tests/unit/security/pib/identity.t.cpp
index be2d03b..70252d9 100644
--- a/tests/unit/security/pib/identity.t.cpp
+++ b/tests/unit/security/pib/identity.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,13 +25,11 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 BOOST_FIXTURE_TEST_SUITE(TestIdentity, PibDataFixture)
 
 BOOST_AUTO_TEST_CASE(ValidityChecking)
@@ -41,7 +39,7 @@
   BOOST_TEST(id == Identity());
   BOOST_CHECK_THROW(id.getName(), std::domain_error);
 
-  auto impl = std::make_shared<detail::IdentityImpl>(id1, makePibWithIdentity(id1));
+  auto impl = std::make_shared<IdentityImpl>(id1, makePibWithIdentity(id1));
   id = Identity(impl);
   BOOST_TEST(id);
   BOOST_TEST(id != Identity());
@@ -52,12 +50,12 @@
   BOOST_CHECK_THROW(id.getName(), std::domain_error);
 }
 
-// pib::Identity is a wrapper of pib::detail::IdentityImpl. Since the functionality
-// of IdentityImpl is already tested in identity-impl.t.cpp, we only test the shared
-// property of pib::Identity in this test case.
+// pib::Identity is a wrapper of pib::IdentityImpl. Since the functionality
+// of IdentityImpl is already tested in identity-impl.t.cpp, we only test
+// the shared property of pib::Identity in this test case.
 BOOST_AUTO_TEST_CASE(SharedImpl)
 {
-  auto impl = std::make_shared<detail::IdentityImpl>(id1, makePibWithIdentity(id1));
+  auto impl = std::make_shared<IdentityImpl>(id1, makePibWithIdentity(id1));
   Identity identity1(impl);
   Identity identity2(impl);
 
@@ -66,22 +64,18 @@
   BOOST_TEST(Identity() != identity2);
   BOOST_TEST(Identity() == Identity());
 
-  BOOST_CHECK_THROW(identity2.getKey(id1Key1Name), pib::Pib::Error);
+  BOOST_CHECK_THROW(identity2.getKey(id1Key1Name), Pib::Error);
   identity1.addKey(id1Key1, id1Key1Name);
   BOOST_TEST(identity2.getKey(id1Key1Name));
 
   identity2.removeKey(id1Key1Name);
-  BOOST_CHECK_THROW(identity1.getKey(id1Key1Name), pib::Pib::Error);
+  BOOST_CHECK_THROW(identity1.getKey(id1Key1Name), Pib::Error);
 
   identity1.setDefaultKey(id1Key1, id1Key1Name);
   BOOST_TEST(identity2.getDefaultKey().getName() == id1Key1Name);
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestIdentity
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/impl/identity-impl.t.cpp b/tests/unit/security/pib/impl/identity-impl.t.cpp
index 3f38e0e..6b44993 100644
--- a/tests/unit/security/pib/impl/identity-impl.t.cpp
+++ b/tests/unit/security/pib/impl/identity-impl.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,18 +24,13 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace detail {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 
-using pib::Pib;
-
-class IdentityImplFixture : public pib::tests::PibDataFixture
+class IdentityImplFixture : public PibDataFixture
 {
 protected:
   const shared_ptr<PibImpl> pibImpl = makePibWithIdentity(id1);
@@ -136,11 +131,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestIdentityImpl
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace detail
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/impl/key-impl.t.cpp b/tests/unit/security/pib/impl/key-impl.t.cpp
index 4cb960a..940974b 100644
--- a/tests/unit/security/pib/impl/key-impl.t.cpp
+++ b/tests/unit/security/pib/impl/key-impl.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,18 +25,13 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace detail {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 
-using pib::Pib;
-
-class KeyImplFixture : public pib::tests::PibDataFixture
+class KeyImplFixture : public PibDataFixture
 {
 protected:
   const shared_ptr<PibImpl> pibImpl = makePibWithKey(id1Key1Name, id1Key1);
@@ -114,8 +109,7 @@
   BOOST_CHECK_THROW(key11.getDefaultCertificate(), Pib::Error);
 }
 
-class ReplaceFixture : public ndn::tests::KeyChainFixture,
-                       public KeyImplFixture
+class ReplaceFixture : public KeyChainFixture, public KeyImplFixture
 {
 };
 
@@ -126,8 +120,8 @@
 
   auto otherCert = id1Key1Cert1;
   SignatureInfo info;
-  info.setValidityPeriod(ValidityPeriod::makeRelative(-1_s, 10_s));
-  m_keyChain.sign(otherCert, SigningInfo().setSignatureInfo(info));
+  info.setValidityPeriod(security::ValidityPeriod::makeRelative(-1_s, 10_s));
+  m_keyChain.sign(otherCert, security::SigningInfo().setSignatureInfo(info));
   BOOST_TEST(otherCert.getName() == id1Key1Cert1.getName());
   BOOST_TEST(otherCert.getContent() == id1Key1Cert1.getContent());
   BOOST_TEST(otherCert != id1Key1Cert1);
@@ -162,11 +156,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestKeyImpl
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace detail
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/key-container.t.cpp b/tests/unit/security/pib/key-container.t.cpp
index b126bc2..84a4d3f 100644
--- a/tests/unit/security/pib/key-container.t.cpp
+++ b/tests/unit/security/pib/key-container.t.cpp
@@ -26,15 +26,13 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 NDN_CXX_ASSERT_FORWARD_ITERATOR(KeyContainer::const_iterator);
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 BOOST_FIXTURE_TEST_SUITE(TestKeyContainer, PibDataFixture)
 
 BOOST_AUTO_TEST_CASE(AddGetRemove)
@@ -79,8 +77,8 @@
     BOOST_TEST(key1.getPublicKey() == id1Key1, boost::test_tools::per_element());
     BOOST_CHECK_EQUAL(key2.getName(), id1Key2Name);
     BOOST_TEST(key2.getPublicKey() == id1Key2, boost::test_tools::per_element());
-    Name id1Key3Name = constructKeyName(id1, name::Component("non-existing-id"));
-    BOOST_CHECK_THROW(container.get(id1Key3Name), pib::Pib::Error);
+    Name id1Key3Name = security::constructKeyName(id1, name::Component("non-existing-id"));
+    BOOST_CHECK_THROW(container.get(id1Key3Name), Pib::Error);
   }
 
   {
@@ -167,10 +165,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestKeyContainer
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/key.t.cpp b/tests/unit/security/pib/key.t.cpp
index 4d1da0c..5273436 100644
--- a/tests/unit/security/pib/key.t.cpp
+++ b/tests/unit/security/pib/key.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,13 +25,11 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 BOOST_FIXTURE_TEST_SUITE(TestKey, PibDataFixture)
 
 BOOST_AUTO_TEST_CASE(ValidityChecking)
@@ -41,8 +39,7 @@
   BOOST_TEST(key == Key());
   BOOST_CHECK_THROW(key.getName(), std::domain_error);
 
-  auto impl = std::make_shared<detail::KeyImpl>(id1Key1Name, id1Key1,
-                                                makePibWithKey(id1Key1Name, id1Key1));
+  auto impl = std::make_shared<KeyImpl>(id1Key1Name, id1Key1, makePibWithKey(id1Key1Name, id1Key1));
   key = Key(impl);
   BOOST_TEST(key);
   BOOST_TEST(key != Key());
@@ -53,13 +50,12 @@
   BOOST_CHECK_THROW(key.getName(), std::domain_error);
 }
 
-// pib::Key is a wrapper of pib::detail::KeyImpl. Since the functionality of KeyImpl is
-// already tested in key-impl.t.cpp, we only test the shared property of pib::Key in
-// this test case.
+// pib::Key is a wrapper of pib::KeyImpl. Since the functionality of KeyImpl is
+// already tested in key-impl.t.cpp, we only test the shared property of pib::Key
+// in this test case.
 BOOST_AUTO_TEST_CASE(SharedImpl)
 {
-  auto keyImpl = std::make_shared<detail::KeyImpl>(id1Key1Name, id1Key1,
-                                                   makePibWithKey(id1Key1Name, id1Key1));
+  auto keyImpl = std::make_shared<KeyImpl>(id1Key1Name, id1Key1, makePibWithKey(id1Key1Name, id1Key1));
   Key key1(keyImpl);
   Key key2(keyImpl);
 
@@ -68,12 +64,12 @@
   BOOST_TEST(Key() != key2);
   BOOST_TEST(Key() == Key());
 
-  BOOST_CHECK_THROW(key2.getCertificate(id1Key1Cert1.getName()), pib::Pib::Error);
+  BOOST_CHECK_THROW(key2.getCertificate(id1Key1Cert1.getName()), Pib::Error);
   key1.addCertificate(id1Key1Cert1);
   BOOST_TEST(key2.getCertificate(id1Key1Cert1.getName()) == id1Key1Cert1);
 
   key2.removeCertificate(id1Key1Cert1.getName());
-  BOOST_CHECK_THROW(key1.getCertificate(id1Key1Cert1.getName()), pib::Pib::Error);
+  BOOST_CHECK_THROW(key1.getCertificate(id1Key1Cert1.getName()), Pib::Error);
 
   key1.setDefaultCertificate(id1Key1Cert1);
   BOOST_TEST(key2.getDefaultCertificate() == id1Key1Cert1);
@@ -81,6 +77,10 @@
 
 BOOST_AUTO_TEST_CASE(Helpers)
 {
+  using ndn::security::constructKeyName;
+  using ndn::security::isValidKeyName;
+  using ndn::security::extractIdentityFromKeyName;
+
   BOOST_CHECK_EQUAL(constructKeyName("/hello", name::Component("world")), "/hello/KEY/world");
 
   BOOST_CHECK_EQUAL(isValidKeyName("/hello"), false);
@@ -98,10 +98,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestKey
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/pib-data-fixture.cpp b/tests/unit/security/pib/pib-data-fixture.cpp
index 488d11e..dde1d8b 100644
--- a/tests/unit/security/pib/pib-data-fixture.cpp
+++ b/tests/unit/security/pib/pib-data-fixture.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,10 +30,10 @@
 
 // #include <iostream>
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security;
+using namespace ndn::security::pib;
 
 // class TestCertDataGenerator
 // {
@@ -95,8 +95,8 @@
 //   }
 
 // private:
-//   pib::PibMemory pib;
-//   Tpm tpm{"test", "test", make_unique<tpm::BackEndMem>()};
+//   PibMemory pib;
+//   Tpm tpm{"test:test", make_unique<tpm::BackEndMem>()};
 // };
 
 // // The test data can be generated using this test case
@@ -414,7 +414,4 @@
   return pib;
 }
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/pib-data-fixture.hpp b/tests/unit/security/pib/pib-data-fixture.hpp
index 64c8652..7fcdebb 100644
--- a/tests/unit/security/pib/pib-data-fixture.hpp
+++ b/tests/unit/security/pib/pib-data-fixture.hpp
@@ -25,20 +25,19 @@
 #include "ndn-cxx/security/certificate.hpp"
 #include "ndn-cxx/security/pib/pib-impl.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::security::Certificate;
 
 class PibDataFixture
 {
 public:
   PibDataFixture();
 
-  [[nodiscard]] static shared_ptr<PibImpl>
+  [[nodiscard]] static shared_ptr<security::pib::PibImpl>
   makePibWithIdentity(const Name& idName);
 
-  [[nodiscard]] static shared_ptr<PibImpl>
+  [[nodiscard]] static shared_ptr<security::pib::PibImpl>
   makePibWithKey(const Name& keyName, span<const uint8_t> key);
 
 public:
@@ -65,9 +64,6 @@
   Buffer id2Key2;
 };
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_SECURITY_PIB_PIB_DATA_FIXTURE_HPP
diff --git a/tests/unit/security/pib/pib-impl.t.cpp b/tests/unit/security/pib/pib-impl.t.cpp
index d88bad6..b26109d 100644
--- a/tests/unit/security/pib/pib-impl.t.cpp
+++ b/tests/unit/security/pib/pib-impl.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -29,17 +29,13 @@
 #include <boost/filesystem.hpp>
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 BOOST_AUTO_TEST_SUITE(TestPibImpl)
 
-using pib::Pib;
-
 class PibMemoryFixture : public PibDataFixture
 {
 public:
@@ -336,10 +332,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestPibImpl
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/pib/pib.t.cpp b/tests/unit/security/pib/pib.t.cpp
index 8d668e5..3a665c3 100644
--- a/tests/unit/security/pib/pib.t.cpp
+++ b/tests/unit/security/pib/pib.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,17 +25,13 @@
 #include "tests/boost-test.hpp"
 #include "tests/unit/security/pib/pib-data-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace pib {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::pib;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Pib)
 BOOST_FIXTURE_TEST_SUITE(TestPib, PibDataFixture)
 
-using pib::Pib;
-
 BOOST_AUTO_TEST_CASE(TpmLocator)
 {
   Pib pib("pib-memory:", make_shared<PibMemory>());
@@ -116,10 +112,6 @@
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestPib
-BOOST_AUTO_TEST_SUITE_END() // Pib
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace pib
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/safe-bag.t.cpp b/tests/unit/security/safe-bag.t.cpp
index ade7f69..9f9b00d 100644
--- a/tests/unit/security/safe-bag.t.cpp
+++ b/tests/unit/security/safe-bag.t.cpp
@@ -25,9 +25,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::security::SafeBag;
 
 BOOST_CONCEPT_ASSERT((WireEncodable<SafeBag>));
 BOOST_CONCEPT_ASSERT((WireDecodable<SafeBag>));
@@ -162,6 +162,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSafeBag
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/signing-helpers.t.cpp b/tests/unit/security/signing-helpers.t.cpp
index a515c16..c7065a2 100644
--- a/tests/unit/security/signing-helpers.t.cpp
+++ b/tests/unit/security/signing-helpers.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::security::SigningInfo;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestSigningHelpers)
@@ -64,6 +64,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSigningHelpers
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/signing-info.t.cpp b/tests/unit/security/signing-info.t.cpp
index 87c347f..a1aee15 100644
--- a/tests/unit/security/signing-info.t.cpp
+++ b/tests/unit/security/signing-info.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,9 @@
 #include <boost/lexical_cast.hpp>
 #include <sstream>
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestSigningInfo)
@@ -288,6 +288,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSigningInfo
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/tpm/back-end-wrapper-file.hpp b/tests/unit/security/tpm/back-end-wrapper-file.hpp
index 2da77aa..6d8a663 100644
--- a/tests/unit/security/tpm/back-end-wrapper-file.hpp
+++ b/tests/unit/security/tpm/back-end-wrapper-file.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,10 +26,7 @@
 
 #include <boost/filesystem.hpp>
 
-namespace ndn {
-namespace security {
-namespace tpm {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * @brief A wrapper of tpm::BackEndFile for unit test template.
@@ -39,7 +36,7 @@
 public:
   BackEndWrapperFile()
     : m_tmpPath(boost::filesystem::path(UNIT_TESTS_TMPDIR) / "TpmBackEndFile")
-    , m_impl(make_unique<BackEndFile>(m_tmpPath.string()))
+    , m_impl(make_unique<security::tpm::BackEndFile>(m_tmpPath.string()))
   {
   }
 
@@ -48,7 +45,7 @@
     boost::filesystem::remove_all(m_tmpPath);
   }
 
-  BackEnd&
+  security::tpm::BackEnd&
   getTpm()
   {
     return *m_impl;
@@ -62,12 +59,9 @@
 
 private:
   const boost::filesystem::path m_tmpPath;
-  const unique_ptr<BackEnd> m_impl;
+  const unique_ptr<security::tpm::BackEnd> m_impl;
 };
 
-} // namespace tests
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_SECURITY_TPM_BACK_END_WRAPPER_FILE_HPP
diff --git a/tests/unit/security/tpm/back-end-wrapper-mem.hpp b/tests/unit/security/tpm/back-end-wrapper-mem.hpp
index 8de2b12..20dae82 100644
--- a/tests/unit/security/tpm/back-end-wrapper-mem.hpp
+++ b/tests/unit/security/tpm/back-end-wrapper-mem.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,10 +24,7 @@
 
 #include "ndn-cxx/security/tpm/impl/back-end-mem.hpp"
 
-namespace ndn {
-namespace security {
-namespace tpm {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * @brief A wrapper of tpm::BackEndMem for unit test template.
@@ -36,11 +33,11 @@
 {
 public:
   BackEndWrapperMem()
-    : m_impl(make_unique<BackEndMem>())
+    : m_impl(make_unique<security::tpm::BackEndMem>())
   {
   }
 
-  BackEnd&
+  security::tpm::BackEnd&
   getTpm()
   {
     return *m_impl;
@@ -53,12 +50,9 @@
   }
 
 private:
-  const unique_ptr<BackEnd> m_impl;
+  const unique_ptr<security::tpm::BackEnd> m_impl;
 };
 
-} // namespace tests
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_SECURITY_TPM_BACK_END_WRAPPER_MEM_HPP
diff --git a/tests/unit/security/tpm/back-end-wrapper-osx.hpp b/tests/unit/security/tpm/back-end-wrapper-osx.hpp
index c459c47..542c319 100644
--- a/tests/unit/security/tpm/back-end-wrapper-osx.hpp
+++ b/tests/unit/security/tpm/back-end-wrapper-osx.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,10 +27,7 @@
 
 #include <cstdlib>
 
-namespace ndn {
-namespace security {
-namespace tpm {
-namespace tests {
+namespace ndn::tests {
 
 /**
  * @brief A wrapper of tpm::BackEndOsx for unit test template.
@@ -52,7 +49,7 @@
     else
       unsetenv("HOME");
 
-    m_impl = make_unique<BackEndOsx>();
+    m_impl = make_unique<security::tpm::BackEndOsx>();
   }
 
   ~BackEndWrapperOsx()
@@ -63,7 +60,7 @@
       unsetenv("HOME");
   }
 
-  BackEnd&
+  security::tpm::BackEnd&
   getTpm()
   {
     return *m_impl;
@@ -77,12 +74,9 @@
 
 private:
   std::string m_HOME;
-  unique_ptr<BackEnd> m_impl;
+  unique_ptr<security::tpm::BackEnd> m_impl;
 };
 
-} // namespace tests
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_SECURITY_TPM_BACK_END_WRAPPER_OSX_HPP
diff --git a/tests/unit/security/tpm/back-end.t.cpp b/tests/unit/security/tpm/back-end.t.cpp
index 78f09e3..34d79b4 100644
--- a/tests/unit/security/tpm/back-end.t.cpp
+++ b/tests/unit/security/tpm/back-end.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -41,16 +41,14 @@
 #include <boost/mpl/vector.hpp>
 #include <set>
 
-namespace ndn {
-namespace security {
-namespace tpm {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security;
+using ndn::security::tpm::BackEnd;
+using ndn::security::tpm::KeyHandle;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(Tpm)
-BOOST_AUTO_TEST_SUITE(TestBackEnd)
-
-using tpm::Tpm;
+BOOST_AUTO_TEST_SUITE(TestTpmBackEnd)
 
 using TestBackEnds = boost::mpl::vector<
 #if defined(NDN_CXX_HAVE_OSX_FRAMEWORKS) && defined(NDN_CXX_WITH_OSX_KEYCHAIN)
@@ -354,11 +352,7 @@
   }
 }
 
-BOOST_AUTO_TEST_SUITE_END() // TestBackEnd
-BOOST_AUTO_TEST_SUITE_END() // Tpm
+BOOST_AUTO_TEST_SUITE_END() // TestTpmBackEnd
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace tpm
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform.t.cpp b/tests/unit/security/transform.t.cpp
deleted file mode 100644
index 901839b..0000000
--- a/tests/unit/security/transform.t.cpp
+++ /dev/null
@@ -1,83 +0,0 @@
-/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2013-2019 Regents of the University of California.
- *
- * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
- *
- * ndn-cxx library is free software: you can redistribute it and/or modify it under the
- * terms of the GNU Lesser General Public License as published by the Free Software
- * Foundation, either version 3 of the License, or (at your option) any later version.
- *
- * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
- * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
- *
- * You should have received copies of the GNU General Public License and GNU Lesser
- * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
- * <http://www.gnu.org/licenses/>.
- *
- * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
- */
-
-#include "ndn-cxx/security/transform.hpp"
-
-#include "tests/boost-test.hpp"
-
-namespace ndn {
-namespace security {
-namespace tests {
-
-BOOST_AUTO_TEST_SUITE(Security)
-BOOST_AUTO_TEST_SUITE(TestTransform)
-
-BOOST_AUTO_TEST_CASE(SymbolVisibility)
-{
-  transform::BufferSource* bufferSource = nullptr;
-  BOOST_CHECK(bufferSource == nullptr);
-
-  transform::StreamSource* streamSource = nullptr;
-  BOOST_CHECK(streamSource == nullptr);
-
-  transform::StepSource* stepSource = nullptr;
-  BOOST_CHECK(stepSource == nullptr);
-
-  transform::BoolSink* boolSink = nullptr;
-  BOOST_CHECK(boolSink == nullptr);
-
-  transform::StreamSink* streamSink = nullptr;
-  BOOST_CHECK(streamSink == nullptr);
-
-  transform::HexEncode* hexEncode = nullptr;
-  BOOST_CHECK(hexEncode == nullptr);
-
-  transform::StripSpace* stripSpace = nullptr;
-  BOOST_CHECK(stripSpace == nullptr);
-
-  transform::HexDecode* hexDecode = nullptr;
-  BOOST_CHECK(hexDecode == nullptr);
-
-  transform::Base64Encode* base64Encode = nullptr;
-  BOOST_CHECK(base64Encode == nullptr);
-
-  transform::Base64Decode* base64Decode = nullptr;
-  BOOST_CHECK(base64Decode == nullptr);
-
-  transform::DigestFilter* digestFilter = nullptr;
-  BOOST_CHECK(digestFilter == nullptr);
-
-  transform::BlockCipher* blockCipher = nullptr;
-  BOOST_CHECK(blockCipher == nullptr);
-
-  transform::SignerFilter* signerFilter = nullptr;
-  BOOST_CHECK(signerFilter == nullptr);
-
-  transform::VerifierFilter* verifierFilter = nullptr;
-  BOOST_CHECK(verifierFilter == nullptr);
-}
-
-BOOST_AUTO_TEST_SUITE_END() // TestTransform
-BOOST_AUTO_TEST_SUITE_END() // Security
-
-} // namespace tests
-} // namespace security
-} // namespace ndn
diff --git a/tests/unit/security/transform/base64-decode.t.cpp b/tests/unit/security/transform/base64-decode.t.cpp
index 5d89fe6..f180624 100644
--- a/tests/unit/security/transform/base64-decode.t.cpp
+++ b/tests/unit/security/transform/base64-decode.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,10 +27,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -173,7 +172,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/base64-encode.t.cpp b/tests/unit/security/transform/base64-encode.t.cpp
index 7b4aa47..c25ecba 100644
--- a/tests/unit/security/transform/base64-encode.t.cpp
+++ b/tests/unit/security/transform/base64-encode.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,10 +28,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -171,7 +170,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/block-cipher.t.cpp b/tests/unit/security/transform/block-cipher.t.cpp
index d8b3c3b..cd857c1 100644
--- a/tests/unit/security/transform/block-cipher.t.cpp
+++ b/tests/unit/security/transform/block-cipher.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,10 +27,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -106,7 +105,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/bool-sink.t.cpp b/tests/unit/security/transform/bool-sink.t.cpp
index a7640c6..be10b13 100644
--- a/tests/unit/security/transform/bool-sink.t.cpp
+++ b/tests/unit/security/transform/bool-sink.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -41,7 +40,7 @@
   BOOST_CHECK_EQUAL(sink1.write({in1 + 1, 1}), 1);
   sink1.end();
   BOOST_CHECK_EQUAL(value1, false);
-  BOOST_CHECK_THROW(sink1.write({in1 + 1, 1}), transform::Error);
+  BOOST_CHECK_THROW(sink1.write({in1 + 1, 1}), Error);
 
   const uint8_t in2[] = {0x01, 0x00};
   bool value2 = false;
@@ -50,14 +49,11 @@
   BOOST_CHECK_EQUAL(sink2.write({in2 + 1, 1}), 1);
   sink2.end();
   BOOST_CHECK_EQUAL(value2, true);
-  BOOST_CHECK_THROW(sink2.write({in2 + 1, 1}), transform::Error);
+  BOOST_CHECK_THROW(sink2.write({in2 + 1, 1}), Error);
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestBoolSink
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/buffer-source.t.cpp b/tests/unit/security/transform/buffer-source.t.cpp
index f957282..aa27644 100644
--- a/tests/unit/security/transform/buffer-source.t.cpp
+++ b/tests/unit/security/transform/buffer-source.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,10 +24,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -91,7 +90,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/digest-filter.t.cpp b/tests/unit/security/transform/digest-filter.t.cpp
index 08f85cf..c414d17 100644
--- a/tests/unit/security/transform/digest-filter.t.cpp
+++ b/tests/unit/security/transform/digest-filter.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,10 +30,9 @@
 
 #include <openssl/evp.h>
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -215,7 +214,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/hex-decode.t.cpp b/tests/unit/security/transform/hex-decode.t.cpp
index 23ca9aa..51a2672 100644
--- a/tests/unit/security/transform/hex-decode.t.cpp
+++ b/tests/unit/security/transform/hex-decode.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,10 +28,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -262,11 +261,11 @@
 {
   const std::string in1 = "0001020304050";
   OBufferStream os1;
-  BOOST_CHECK_THROW(bufferSource(in1) >> hexDecode() >> streamSink(os1), transform::Error);
+  BOOST_CHECK_THROW(bufferSource(in1) >> hexDecode() >> streamSink(os1), Error);
 
   const std::string in2 = "0001020304xy";
   OBufferStream os2;
-  BOOST_CHECK_THROW(bufferSource(in2) >> hexDecode() >> streamSink(os2), transform::Error);
+  BOOST_CHECK_THROW(bufferSource(in2) >> hexDecode() >> streamSink(os2), Error);
 }
 
 BOOST_AUTO_TEST_CASE(EmptyInput)
@@ -283,7 +282,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/hex-encode.t.cpp b/tests/unit/security/transform/hex-encode.t.cpp
index 8025c37..2a81b6a 100644
--- a/tests/unit/security/transform/hex-encode.t.cpp
+++ b/tests/unit/security/transform/hex-encode.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,10 +27,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -176,7 +175,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/private-key.t.cpp b/tests/unit/security/transform/private-key.t.cpp
index 077c2e3..f9a511d 100644
--- a/tests/unit/security/transform/private-key.t.cpp
+++ b/tests/unit/security/transform/private-key.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -38,10 +38,9 @@
 #include <boost/mpl/vector.hpp>
 #include <sstream>
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -716,7 +715,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/public-key.t.cpp b/tests/unit/security/transform/public-key.t.cpp
index 655811c..31970c4 100644
--- a/tests/unit/security/transform/public-key.t.cpp
+++ b/tests/unit/security/transform/public-key.t.cpp
@@ -32,10 +32,9 @@
 
 #include <sstream>
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -151,7 +150,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/signer-filter.t.cpp b/tests/unit/security/transform/signer-filter.t.cpp
index cad6f04..ad3b788 100644
--- a/tests/unit/security/transform/signer-filter.t.cpp
+++ b/tests/unit/security/transform/signer-filter.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,10 +31,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -92,7 +91,7 @@
   bufferSource(data) >> signerFilter(DigestAlgorithm::SHA256, sKey) >> streamSink(os2);
   auto sig = os2.buf();
 
-  BOOST_TEST(verifySignature({data}, *sig, *pubKey));
+  BOOST_TEST(security::verifySignature({data}, *sig, *pubKey));
 }
 
 BOOST_AUTO_TEST_CASE(Ecdsa)
@@ -130,7 +129,7 @@
   bufferSource(data) >> signerFilter(DigestAlgorithm::SHA256, sKey) >> streamSink(os2);
   auto sig = os2.buf();
 
-  BOOST_TEST(verifySignature({data}, *sig, *pubKey));
+  BOOST_TEST(security::verifySignature({data}, *sig, *pubKey));
 }
 
 BOOST_AUTO_TEST_SUITE(Hmac)
@@ -244,7 +243,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/step-source.t.cpp b/tests/unit/security/transform/step-source.t.cpp
index 0179011..c950716 100644
--- a/tests/unit/security/transform/step-source.t.cpp
+++ b/tests/unit/security/transform/step-source.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,10 +26,9 @@
 
 #include <sstream>
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -69,7 +68,7 @@
   BOOST_CHECK_EQUAL(ss.write({buf + 960, 320}), 320);
   ss.end();
 
-  BOOST_CHECK_THROW(ss.write({buf + 960, 320}), transform::Error);
+  BOOST_CHECK_THROW(ss.write({buf + 960, 320}), Error);
   BOOST_CHECK_EQUAL(os.str(), input);
 }
 
@@ -87,7 +86,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/stream-sink.t.cpp b/tests/unit/security/transform/stream-sink.t.cpp
index f58bece..b79012d 100644
--- a/tests/unit/security/transform/stream-sink.t.cpp
+++ b/tests/unit/security/transform/stream-sink.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,10 +23,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -48,14 +47,11 @@
 
   std::string out = os.str();
   BOOST_CHECK_EQUAL_COLLECTIONS(in, in + sizeof(in), out.begin(), out.end());
-  BOOST_CHECK_THROW(sink.write({in + 8, 8}), transform::Error);
+  BOOST_CHECK_THROW(sink.write({in + 8, 8}), Error);
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestStreamSink
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/stream-source.t.cpp b/tests/unit/security/transform/stream-source.t.cpp
index 1446bc9..e20ff23 100644
--- a/tests/unit/security/transform/stream-source.t.cpp
+++ b/tests/unit/security/transform/stream-source.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,10 +27,9 @@
 #include <boost/mpl/integral_c.hpp>
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -77,24 +76,21 @@
   BOOST_CHECK_EQUAL(os.str(), "");
 }
 
-typedef boost::mpl::vector<
+using BadBits = boost::mpl::vector<
   boost::mpl::integral_c<std::ios_base::iostate, std::ios_base::badbit>,
   boost::mpl::integral_c<std::ios_base::iostate, std::ios_base::failbit>
-> BadBits;
+>;
 
 BOOST_AUTO_TEST_CASE_TEMPLATE(BadStream, BadBit, BadBits)
 {
   std::stringstream is;
   is.setstate(BadBit::value);
   std::stringstream os;
-  BOOST_CHECK_THROW(streamSource(is) >> streamSink(os), transform::Error);
+  BOOST_CHECK_THROW(streamSource(is) >> streamSink(os), Error);
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestStreamSource
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/strip-space.t.cpp b/tests/unit/security/transform/strip-space.t.cpp
index cd73270..cbc406d 100644
--- a/tests/unit/security/transform/strip-space.t.cpp
+++ b/tests/unit/security/transform/strip-space.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,10 +27,9 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -72,7 +71,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/transform/verifier-filter.t.cpp b/tests/unit/security/transform/verifier-filter.t.cpp
index ef986b1..e04415c 100644
--- a/tests/unit/security/transform/verifier-filter.t.cpp
+++ b/tests/unit/security/transform/verifier-filter.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -35,10 +35,9 @@
 
 #include <openssl/opensslv.h>
 
-namespace ndn {
-namespace security {
-namespace transform {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::transform;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(Transform)
@@ -188,7 +187,4 @@
 BOOST_AUTO_TEST_SUITE_END() // Transform
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace transform
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/trust-anchor-container.t.cpp b/tests/unit/security/trust-anchor-container.t.cpp
index 09825db..0e76214 100644
--- a/tests/unit/security/trust-anchor-container.t.cpp
+++ b/tests/unit/security/trust-anchor-container.t.cpp
@@ -27,17 +27,12 @@
 
 #include <boost/filesystem/operations.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
-/**
- * This fixture creates a directory and prepares two certificates.
- * cert1 is written to a file under the directory, while cert2 is not.
- */
+// This fixture creates a directory and prepares two certificates.
+// cert1 is written to a file under the directory, while cert2 is not.
 class TrustAnchorContainerFixture : public ClockFixture, public KeyChainFixture
 {
 public:
@@ -196,7 +191,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestTrustAnchorContainer
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validation-error.t.cpp b/tests/unit/security/validation-error.t.cpp
index c4a1a08..f59d6e7 100644
--- a/tests/unit/security/validation-error.t.cpp
+++ b/tests/unit/security/validation-error.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,10 +25,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::security::ValidationError;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestValidationError)
@@ -59,7 +58,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidationError
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validation-policy-accept-all.t.cpp b/tests/unit/security/validation-policy-accept-all.t.cpp
index cd94cf7..ca86c86 100644
--- a/tests/unit/security/validation-policy-accept-all.t.cpp
+++ b/tests/unit/security/validation-policy-accept-all.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,16 +26,11 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Security)
 
-class ValidationPolicyAcceptAllFixture : public ValidatorFixture<ValidationPolicyAcceptAll>
+class ValidationPolicyAcceptAllFixture : public ValidatorFixture<security::ValidationPolicyAcceptAll>
 {
 public:
   ValidationPolicyAcceptAllFixture()
@@ -50,7 +45,7 @@
 
 BOOST_FIXTURE_TEST_SUITE(TestValidationPolicyAcceptAll, ValidationPolicyAcceptAllFixture)
 
-typedef boost::mpl::vector<Interest, Data> Packets;
+using Packets = boost::mpl::vector<Interest, Data>;
 
 BOOST_AUTO_TEST_CASE_TEMPLATE(Validate, Packet, Packets)
 {
@@ -71,7 +66,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidationPolicyAcceptAll
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validation-policy-command-interest.t.cpp b/tests/unit/security/validation-policy-command-interest.t.cpp
index 971b509..ac690e7 100644
--- a/tests/unit/security/validation-policy-command-interest.t.cpp
+++ b/tests/unit/security/validation-policy-command-interest.t.cpp
@@ -30,12 +30,9 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 
@@ -535,7 +532,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidationPolicyCommandInterest
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validation-policy-config.t.cpp b/tests/unit/security/validation-policy-config.t.cpp
index 83c6f52..07b98e9 100644
--- a/tests/unit/security/validation-policy-config.t.cpp
+++ b/tests/unit/security/validation-policy-config.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,14 +30,9 @@
 #include "tests/unit/security/validator-config/common.hpp"
 #include "tests/unit/security/validator-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
-using namespace ndn::security::tests;
+using ndn::security::ValidationPolicyConfig;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestValidationPolicyConfig)
@@ -760,6 +755,8 @@
 
 BOOST_FIXTURE_TEST_CASE(OrphanedPolicyLoad, HierarchicalValidatorFixture<ValidationPolicyConfig>) // Bug #4758
 {
+  using ndn::security::validator_config::Error;
+
   ValidationPolicyConfig policy1;
   BOOST_CHECK_THROW(policy1.load("trust-anchor { type any }", "test-config"), Error);
 
@@ -767,8 +764,7 @@
   BOOST_CHECK_THROW(policy1.load("trust-anchor { type any }", "test-config"), Error);
 
   ValidationPolicyConfig policy2;
-
-  std::string config = R"CONF(
+  const std::string config = R"CONF(
       trust-anchor
       {
         type dir
@@ -776,7 +772,6 @@
         refresh 1h
       }
     )CONF";
-
   // Inserting trust anchor would have triggered a segfault
   BOOST_CHECK_THROW(policy2.load(config, "test-config"), Error);
 }
@@ -784,8 +779,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidationPolicyConfig
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validation-policy-signed-interest.t.cpp b/tests/unit/security/validation-policy-signed-interest.t.cpp
index 58f502e..ded8825 100644
--- a/tests/unit/security/validation-policy-signed-interest.t.cpp
+++ b/tests/unit/security/validation-policy-signed-interest.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -30,12 +30,9 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 
@@ -525,7 +522,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidationPolicySignedInterest
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validation-policy-simple-hierarchy.t.cpp b/tests/unit/security/validation-policy-simple-hierarchy.t.cpp
index 788a7c9..80fc58a 100644
--- a/tests/unit/security/validation-policy-simple-hierarchy.t.cpp
+++ b/tests/unit/security/validation-policy-simple-hierarchy.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,14 +26,11 @@
 
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_FIXTURE_TEST_SUITE(TestValidationPolicySimpleHierarchy,
-                         HierarchicalValidatorFixture<ValidationPolicySimpleHierarchy>)
+                         HierarchicalValidatorFixture<security::ValidationPolicySimpleHierarchy>)
 
 using Packets = boost::mpl::vector<InterestV03Pkt, DataPkt>;
 
@@ -125,7 +122,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidationPolicySimpleHierarchy
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validation-policy.t.cpp b/tests/unit/security/validation-policy.t.cpp
index 3d76f62..3ff9fe8 100644
--- a/tests/unit/security/validation-policy.t.cpp
+++ b/tests/unit/security/validation-policy.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,16 +24,15 @@
 #include "tests/boost-test.hpp"
 #include "tests/key-chain-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_FIXTURE_TEST_SUITE(TestValidationPolicy, ndn::tests::KeyChainFixture)
+BOOST_FIXTURE_TEST_SUITE(TestValidationPolicy, KeyChainFixture)
 
 BOOST_AUTO_TEST_CASE(ExtractIdentityNameFromKeyLocator)
 {
+  using ndn::security::extractIdentityNameFromKeyLocator;
+
   auto id = m_keyChain.createIdentity("/random/identity");
   auto keyName = id.getDefaultKey().getName();
   auto certName = id.getDefaultKey().getDefaultCertificate().getName();
@@ -55,7 +54,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidationPolicy
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator-config.t.cpp b/tests/unit/security/validator-config.t.cpp
index 391879d..7cdfa53 100644
--- a/tests/unit/security/validator-config.t.cpp
+++ b/tests/unit/security/validator-config.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -29,11 +29,7 @@
 #include "tests/key-chain-fixture.hpp"
 #include "tests/unit/security/validator-config/common.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_FIXTURE_TEST_SUITE(TestValidatorConfig, KeyChainFixture)
@@ -42,12 +38,12 @@
 
 BOOST_AUTO_TEST_CASE(Construct)
 {
-  util::DummyClientFace face;
+  DummyClientFace face;
 
   ValidatorConfig v1(face);
   BOOST_CHECK_EQUAL(v1.m_policyConfig.m_isConfigured, false);
 
-  ValidatorConfig v2(make_unique<CertificateFetcherOffline>());
+  ValidatorConfig v2(make_unique<security::CertificateFetcherOffline>());
   BOOST_CHECK_EQUAL(v2.m_policyConfig.m_isConfigured, false);
 }
 
@@ -56,7 +52,7 @@
 public:
   ValidatorConfigFixture()
     : path(boost::filesystem::path(UNIT_TESTS_TMPDIR) / "security" / "validator-config")
-    , validator(make_unique<CertificateFetcherOffline>())
+    , validator(make_unique<security::CertificateFetcherOffline>())
   {
     boost::filesystem::create_directories(path);
     config = R"CONF(
@@ -118,11 +114,11 @@
 
 BOOST_AUTO_TEST_CASE(FromSection)
 {
-  validator.load(validator_config::tests::makeSection(config), "config-file-from-section");
+  validator.load(makeSection(config), "config-file-from-section");
   BOOST_CHECK_EQUAL(validator.m_policyConfig.m_isConfigured, true);
 
   // should reload policy
-  validator.load(validator_config::tests::makeSection(config), "config-file-from-section");
+  validator.load(makeSection(config), "config-file-from-section");
   BOOST_CHECK_EQUAL(validator.m_policyConfig.m_isConfigured, true);
 }
 
@@ -133,7 +129,7 @@
 {
   validator.load(configFile);
 
-  InterestSigner signer(m_keyChain);
+  security::InterestSigner signer(m_keyChain);
   auto i = signer.makeCommandInterest("/hello/world/CMD", signingWithSha256());
   size_t nValidated = 0, nFailed = 0;
 
@@ -155,7 +151,7 @@
 {
   validator.load(configFile);
 
-  InterestSigner signer(m_keyChain);
+  security::InterestSigner signer(m_keyChain);
   Interest i1("/hello/world");
   signer.makeSignedInterest(i1);
   size_t nValidated = 0, nFailed = 0;
@@ -179,7 +175,7 @@
 {
   validator.load(configFile);
 
-  InterestSigner signer(m_keyChain);
+  security::InterestSigner signer(m_keyChain);
   auto i1 = signer.makeCommandInterest("/hello/world");
   size_t nValidated = 0, nFailed = 0;
 
@@ -200,6 +196,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidatorConfig
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator-config/checker.t.cpp b/tests/unit/security/validator-config/checker.t.cpp
index 1170156..6c61085 100644
--- a/tests/unit/security/validator-config/checker.t.cpp
+++ b/tests/unit/security/validator-config/checker.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,14 +27,9 @@
 #include "tests/unit/security/validator-fixture.hpp"
 #include "tests/unit/security/validator-config/common.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
-using namespace ndn::security::tests;
+using namespace ndn::security::validator_config;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(ValidatorConfig)
@@ -343,8 +338,4 @@
 BOOST_AUTO_TEST_SUITE_END() // ValidatorConfig
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator-config/common.hpp b/tests/unit/security/validator-config/common.hpp
index c4a4fe3..c984cf5 100644
--- a/tests/unit/security/validator-config/common.hpp
+++ b/tests/unit/security/validator-config/common.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,11 +26,9 @@
 
 #include <boost/property_tree/info_parser.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::security::validator_config::ConfigSection;
 
 inline ConfigSection
 makeSection(const std::string& config)
@@ -41,10 +39,6 @@
   return section;
 }
 
-} // namespace tests
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_SECURITY_VALIDATOR_CONFIG_COMMON_HPP
diff --git a/tests/unit/security/validator-config/filter.t.cpp b/tests/unit/security/validator-config/filter.t.cpp
index 42eeceb..a83217b 100644
--- a/tests/unit/security/validator-config/filter.t.cpp
+++ b/tests/unit/security/validator-config/filter.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,14 +25,9 @@
 #include "tests/unit/security/validator-config/common.hpp"
 #include "tests/unit/security/validator-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
-using namespace ndn::security::tests;
+using namespace ndn::security::validator_config;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(ValidatorConfig)
@@ -198,8 +193,4 @@
 BOOST_AUTO_TEST_SUITE_END() // ValidatorConfig
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator-config/name-relation.t.cpp b/tests/unit/security/validator-config/name-relation.t.cpp
index 8879212..c81a092 100644
--- a/tests/unit/security/validator-config/name-relation.t.cpp
+++ b/tests/unit/security/validator-config/name-relation.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,11 +25,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security::validator_config;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(ValidatorConfig)
@@ -49,7 +47,7 @@
   BOOST_CHECK_EQUAL(getNameRelationFromString("equal"), NameRelation::EQUAL);
   BOOST_CHECK_EQUAL(getNameRelationFromString("is-prefix-of"), NameRelation::IS_PREFIX_OF);
   BOOST_CHECK_EQUAL(getNameRelationFromString("is-strict-prefix-of"), NameRelation::IS_STRICT_PREFIX_OF);
-  BOOST_CHECK_THROW(getNameRelationFromString("unknown"), validator_config::Error);
+  BOOST_CHECK_THROW(getNameRelationFromString("unknown"), Error);
 }
 
 BOOST_AUTO_TEST_CASE(CheckRelation)
@@ -70,8 +68,4 @@
 BOOST_AUTO_TEST_SUITE_END() // ValidatorConfig
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator-config/rule.t.cpp b/tests/unit/security/validator-config/rule.t.cpp
index 4871521..ea0b4b7 100644
--- a/tests/unit/security/validator-config/rule.t.cpp
+++ b/tests/unit/security/validator-config/rule.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,14 +27,9 @@
 
 #include <boost/mpl/vector_c.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace validator_config {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
-using namespace ndn::security::tests;
+using namespace ndn::security::validator_config;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(ValidatorConfig)
@@ -54,7 +49,7 @@
   const std::string ruleId = "rule-id";
   Rule rule;
   Name pktName;
-  shared_ptr<ValidationState> state;
+  shared_ptr<security::ValidationState> state;
 };
 
 using PktTypes = boost::mpl::vector<DataPkt, InterestV02Pkt, InterestV03Pkt>;
@@ -211,8 +206,4 @@
 BOOST_AUTO_TEST_SUITE_END() // ValidatorConfig
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace validator_config
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator-fixture.cpp b/tests/unit/security/validator-fixture.cpp
index 0e780b4..41497bf 100644
--- a/tests/unit/security/validator-fixture.cpp
+++ b/tests/unit/security/validator-fixture.cpp
@@ -22,11 +22,11 @@
 #include "tests/unit/security/validator-fixture.hpp"
 
 #include "ndn-cxx/security/additional-description.hpp"
+#include "ndn-cxx/util/signal/scoped-connection.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::security;
 
 ValidatorFixtureBase::ValidatorFixtureBase()
 {
@@ -45,7 +45,7 @@
 void
 ValidatorFixtureBase::mockNetworkOperations()
 {
-  util::signal::ScopedConnection conn = face.onSendInterest.connect([this] (const Interest& interest) {
+  signal::ScopedConnection conn = face.onSendInterest.connect([this] (const Interest& interest) {
     if (processInterest) {
       m_io.post([=] { processInterest(interest); });
     }
@@ -102,7 +102,4 @@
   return interest.getName();
 }
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator-fixture.hpp b/tests/unit/security/validator-fixture.hpp
index 39e4ed3..6d69a1e 100644
--- a/tests/unit/security/validator-fixture.hpp
+++ b/tests/unit/security/validator-fixture.hpp
@@ -31,12 +31,13 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-class ValidatorFixtureBase : public ndn::tests::IoKeyChainFixture
+using ndn::security::Certificate;
+using ndn::security::Identity;
+using ndn::security::ValidationError;
+
+class ValidatorFixtureBase : public IoKeyChainFixture
 {
 protected:
   ValidatorFixtureBase();
@@ -63,9 +64,9 @@
   addSubCertificate(const Name& subIdentityName, const Identity& issuer);
 
 protected:
-  util::DummyClientFace face{m_io, {true, true}};
+  DummyClientFace face{m_io, {true, true}};
   std::function<void(const Interest&)> processInterest;
-  CertificateCache cache{100_days};
+  security::CertificateCache cache{100_days};
   ValidationError lastError{ValidationError::NO_ERROR};
 
 private:
@@ -73,7 +74,7 @@
   static constexpr int s_mockTimes{200};
 };
 
-template<class ValidationPolicyT, class CertificateFetcherT = CertificateFetcherFromNetwork>
+template<class ValidationPolicyT, class CertificateFetcherT = security::CertificateFetcherFromNetwork>
 class ValidatorFixture : public ValidatorFixtureBase
 {
 protected:
@@ -109,11 +110,11 @@
   }
 
 protected:
-  Validator validator;
+  security::Validator validator;
   ValidationPolicyT& policy;
 };
 
-template<class ValidationPolicyT, class CertificateFetcherT = CertificateFetcherFromNetwork>
+template<class ValidationPolicyT, class CertificateFetcherT = security::CertificateFetcherFromNetwork>
 class HierarchicalValidatorFixture : public ValidatorFixture<ValidationPolicyT, CertificateFetcherT>
 {
 protected:
@@ -142,7 +143,7 @@
 #define VALIDATE_SUCCESS(packet, message) this->validate(packet, message, true, __LINE__)
 #define VALIDATE_FAILURE(packet, message) this->validate(packet, message, false, __LINE__)
 
-class DummyValidationState : public ValidationState
+class DummyValidationState : public security::ValidationState
 {
 public:
   ~DummyValidationState() override
@@ -190,7 +191,7 @@
     return Data(name);
   }
 
-  static shared_ptr<ValidationState>
+  static shared_ptr<security::ValidationState>
   makeState()
   {
     return make_shared<DummyValidationState>();
@@ -214,11 +215,11 @@
     return Interest(name);
   }
 
-  static shared_ptr<ValidationState>
+  static shared_ptr<security::ValidationState>
   makeState()
   {
     auto state = make_shared<DummyValidationState>();
-    state->setTag(make_shared<SignedInterestFormatTag>(SignedInterestFormat::V02));
+    state->setTag(make_shared<security::SignedInterestFormatTag>(security::SignedInterestFormat::V02));
     return state;
   }
 };
@@ -240,18 +241,15 @@
     return Interest(name);
   }
 
-  static shared_ptr<ValidationState>
+  static shared_ptr<security::ValidationState>
   makeState()
   {
     auto state = make_shared<DummyValidationState>();
-    state->setTag(make_shared<SignedInterestFormatTag>(SignedInterestFormat::V03));
+    state->setTag(make_shared<security::SignedInterestFormatTag>(security::SignedInterestFormat::V03));
     return state;
   }
 };
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_SECURITY_VALIDATOR_FIXTURE_HPP
diff --git a/tests/unit/security/validator-null.t.cpp b/tests/unit/security/validator-null.t.cpp
index 5ad9be5..ebae900 100644
--- a/tests/unit/security/validator-null.t.cpp
+++ b/tests/unit/security/validator-null.t.cpp
@@ -24,12 +24,12 @@
 #include "tests/boost-test.hpp"
 #include "tests/key-chain-fixture.hpp"
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::security::ValidatorNull;
 
 BOOST_AUTO_TEST_SUITE(Security)
-BOOST_FIXTURE_TEST_SUITE(TestValidatorNull, ndn::tests::KeyChainFixture)
+BOOST_FIXTURE_TEST_SUITE(TestValidatorNull, KeyChainFixture)
 
 BOOST_AUTO_TEST_CASE(ValidateData)
 {
@@ -58,6 +58,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidatorNull
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validator.t.cpp b/tests/unit/security/validator.t.cpp
index d1b746b..c56db6a 100644
--- a/tests/unit/security/validator.t.cpp
+++ b/tests/unit/security/validator.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,12 +25,9 @@
 #include "tests/test-common.hpp"
 #include "tests/unit/security/validator-fixture.hpp"
 
-namespace ndn {
-namespace security {
-inline namespace v2 {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_FIXTURE_TEST_SUITE(TestValidator, HierarchicalValidatorFixture<ValidationPolicySimpleHierarchy>)
@@ -378,7 +375,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidator
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // inline namespace v2
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/validity-period.t.cpp b/tests/unit/security/validity-period.t.cpp
index dbcd47f..1fbd6b1 100644
--- a/tests/unit/security/validity-period.t.cpp
+++ b/tests/unit/security/validity-period.t.cpp
@@ -27,11 +27,9 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using ndn::security::ValidityPeriod;
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<ValidityPeriod>));
 BOOST_CONCEPT_ASSERT((WireEncodable<ValidityPeriod>));
@@ -121,8 +119,8 @@
 
 BOOST_AUTO_TEST_CASE(EncodingDecoding)
 {
-  time::system_clock::TimePoint notBefore = time::getUnixEpoch();
-  time::system_clock::TimePoint notAfter = notBefore + 1_day;
+  time::system_clock::time_point notBefore = time::getUnixEpoch();
+  time::system_clock::time_point notAfter = notBefore + 1_day;
   ValidityPeriod v1(notBefore, notAfter);
   BOOST_CHECK_EQUAL_COLLECTIONS(v1.wireEncode().begin(), v1.wireEncode().end(),
                                 VP1, VP1 + sizeof(VP1));
@@ -206,9 +204,9 @@
 
 BOOST_AUTO_TEST_CASE(Comparison)
 {
-  time::system_clock::TimePoint notBefore = time::getUnixEpoch();
-  time::system_clock::TimePoint notAfter = notBefore + 1_day;
-  time::system_clock::TimePoint notAfter2 = notBefore + 2_days;
+  auto notBefore = time::getUnixEpoch();
+  auto notAfter = notBefore + 1_day;
+  auto notAfter2 = notBefore + 2_days;
 
   ValidityPeriod validity1(notBefore, notAfter);
   ValidityPeriod validity2(notBefore, notAfter);
@@ -221,6 +219,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestValidityPeriod
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/security/verification-helpers.t.cpp b/tests/unit/security/verification-helpers.t.cpp
index 83d37da..868333d 100644
--- a/tests/unit/security/verification-helpers.t.cpp
+++ b/tests/unit/security/verification-helpers.t.cpp
@@ -29,11 +29,9 @@
 #include <openssl/opensslv.h>
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace security {
-namespace tests {
+namespace ndn::tests {
 
-using namespace ndn::tests;
+using namespace ndn::security;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestVerificationHelpers)
@@ -680,6 +678,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestVerificationHelpers
 BOOST_AUTO_TEST_SUITE_END() // Security
 
-} // namespace tests
-} // namespace security
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/signature-info.t.cpp b/tests/unit/signature-info.t.cpp
index d538217..8fc459c 100644
--- a/tests/unit/signature-info.t.cpp
+++ b/tests/unit/signature-info.t.cpp
@@ -25,8 +25,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<SignatureInfo>));
 BOOST_CONCEPT_ASSERT((WireEncodable<SignatureInfo>));
@@ -550,5 +549,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestSignatureInfo
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/tag.t.cpp b/tests/unit/tag.t.cpp
index 0cbae22..9b4f1a6 100644
--- a/tests/unit/tag.t.cpp
+++ b/tests/unit/tag.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,14 +23,13 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(TestTag)
 
 BOOST_AUTO_TEST_CASE(SimpleTag)
 {
-  typedef ndn::SimpleTag<int, 3> MyTag;
+  using MyTag = ndn::SimpleTag<int, 3>;
 
   BOOST_CHECK_EQUAL(MyTag::getTypeId(), 3);
   MyTag tag(23361); // explicitly convertible from value type
@@ -41,5 +40,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestTag
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/test-home-env-saver.hpp b/tests/unit/test-home-env-saver.hpp
index 9a04605..db1c2f2 100644
--- a/tests/unit/test-home-env-saver.hpp
+++ b/tests/unit/test-home-env-saver.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 #include <cstdlib>
 #include <string>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 class TestHomeEnvSaver
 {
@@ -50,7 +49,6 @@
   std::string m_HOME;
 };
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_TEST_HOME_ENV_SAVER_HPP
diff --git a/tests/unit/transport/tcp-transport.t.cpp b/tests/unit/transport/tcp-transport.t.cpp
index cb577cc..5d86baa 100644
--- a/tests/unit/transport/tcp-transport.t.cpp
+++ b/tests/unit/transport/tcp-transport.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Transport)
 BOOST_AUTO_TEST_SUITE(TestTcpTransport)
@@ -85,5 +84,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestTcpTransport
 BOOST_AUTO_TEST_SUITE_END() // Transport
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/transport/unix-transport.t.cpp b/tests/unit/transport/unix-transport.t.cpp
index a8946f4..f7c54d6 100644
--- a/tests/unit/transport/unix-transport.t.cpp
+++ b/tests/unit/transport/unix-transport.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,8 +23,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Transport)
 BOOST_AUTO_TEST_SUITE(TestUnixTransport)
@@ -54,5 +53,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestUnixTransport
 BOOST_AUTO_TEST_SUITE_END() // Transport
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/concepts.t.cpp b/tests/unit/util/concepts.t.cpp
index 997f86a..74feee7 100644
--- a/tests/unit/util/concepts.t.cpp
+++ b/tests/unit/util/concepts.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018 Regents of the University of California,
+ * Copyright (c) 2014-2023 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -27,8 +27,7 @@
 
 #include "ndn-cxx/util/concepts.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 class WireEncodableType
 {
@@ -57,5 +56,4 @@
 };
 BOOST_CONCEPT_ASSERT((WireDecodable<WireDecodableType>));
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/config-file.t.cpp b/tests/unit/util/config-file.t.cpp
index 9e098c1..ab8f212 100644
--- a/tests/unit/util/config-file.t.cpp
+++ b/tests/unit/util/config-file.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include <boost/filesystem/operations.hpp>
 #include <cstdlib>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_FIXTURE_TEST_SUITE(TestConfigFile, TestHomeEnvSaver)
@@ -67,5 +66,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestConfigFile
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/dummy-client-face.t.cpp b/tests/unit/util/dummy-client-face.t.cpp
index ad0c3bf..0eea2e6 100644
--- a/tests/unit/util/dummy-client-face.t.cpp
+++ b/tests/unit/util/dummy-client-face.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,11 +25,7 @@
 #include "tests/test-common.hpp"
 #include "tests/unit/io-key-chain-fixture.hpp"
 
-namespace ndn {
-namespace util {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_FIXTURE_TEST_SUITE(TestDummyClientFace, IoKeyChainFixture)
@@ -107,13 +103,13 @@
                           [&] (const InterestFilter&, const Interest& interest) {
                             BOOST_CHECK_EQUAL(interest.getName(), "/face1/data");
                             nFace1Interest++;
-                            face1.put(ndn::tests::makeNack(interest, lp::NackReason::NO_ROUTE));
+                            face1.put(makeNack(interest, lp::NackReason::NO_ROUTE));
                           }, nullptr, nullptr);
   face2.setInterestFilter("/face2",
                           [&] (const InterestFilter&, const Interest& interest) {
                             BOOST_CHECK_EQUAL(interest.getName(), "/face2/data");
                             nFace2Interest++;
-                            face2.put(*ndn::tests::makeData("/face2/data"));
+                            face2.put(*makeData("/face2/data"));
                             return;
                           }, nullptr, nullptr);
 
@@ -175,6 +171,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestDummyClientFace
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/exception.t.cpp b/tests/unit/util/exception.t.cpp
index 49ac2ab..d8184c5 100644
--- a/tests/unit/util/exception.t.cpp
+++ b/tests/unit/util/exception.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,7 @@
 #include <boost/exception/diagnostic_information.hpp>
 #include <boost/exception/get_error_info.hpp>
 
-namespace ndn {
-namespace exception {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestException)
@@ -50,7 +48,7 @@
     BOOST_CHECK(boost::get_error_info<boost::throw_function>(ex) != nullptr);
 
 #ifdef NDN_CXX_HAVE_STACKTRACE
-    auto stack = boost::get_error_info<errinfo_stacktrace>(ex);
+    auto stack = boost::get_error_info<ndn::exception::errinfo_stacktrace>(ex);
     BOOST_REQUIRE(stack != nullptr);
     auto info = boost::diagnostic_information(ex);
     BOOST_TEST_MESSAGE(info);
@@ -106,6 +104,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestException
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace exception
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/indented-stream.t.cpp b/tests/unit/util/indented-stream.t.cpp
index 91da1e3..4994d0d 100644
--- a/tests/unit/util/indented-stream.t.cpp
+++ b/tests/unit/util/indented-stream.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,11 +25,10 @@
 
 #include <boost/test/tools/output_test_stream.hpp>
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
 
 using boost::test_tools::output_test_stream;
+using ndn::util::IndentedStream;
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestIndentedStream)
@@ -77,6 +76,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestIndentedStream
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/io.t.cpp b/tests/unit/util/io.t.cpp
index 9658d04..934648a 100644
--- a/tests/unit/util/io.t.cpp
+++ b/tests/unit/util/io.t.cpp
@@ -27,8 +27,7 @@
 #include <boost/filesystem.hpp>
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestIo)
@@ -398,5 +397,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestIo
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/log-filter-module.cpp b/tests/unit/util/log-filter-module.cpp
index ab55728..371b7d6 100644
--- a/tests/unit/util/log-filter-module.cpp
+++ b/tests/unit/util/log-filter-module.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,7 @@
 
 NDN_LOG_INIT(fm.FilterModule);
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
 
 void
 logFromFilterModule()
@@ -38,7 +36,5 @@
   NDN_LOG_FATAL("fatalFM");
 }
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
 
diff --git a/tests/unit/util/log-module1.cpp b/tests/unit/util/log-module1.cpp
index 4f71102..2070c58 100644
--- a/tests/unit/util/log-module1.cpp
+++ b/tests/unit/util/log-module1.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,7 @@
 
 NDN_LOG_INIT(Module1);
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
 
 void
 logFromModule1()
@@ -38,6 +36,4 @@
   NDN_LOG_FATAL("fatal" << 1);
 }
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/log-module2.cpp b/tests/unit/util/log-module2.cpp
index 994e142..6565488 100644
--- a/tests/unit/util/log-module2.cpp
+++ b/tests/unit/util/log-module2.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -23,9 +23,7 @@
 
 NDN_LOG_INIT(Module2);
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
 
 void
 logFromModule2()
@@ -38,6 +36,4 @@
   NDN_LOG_FATAL("fatal" << 2);
 }
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/logger.t.cpp b/tests/unit/util/logger.t.cpp
index ad742bb..70ba72f 100644
--- a/tests/unit/util/logger.t.cpp
+++ b/tests/unit/util/logger.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,9 +24,11 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::util::Logger;
+using ndn::util::Logging;
+using ndn::util::LogLevel;
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestLogger)
@@ -77,6 +79,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestLogger
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/logging.t.cpp b/tests/unit/util/logging.t.cpp
index 02da03a..937b41b 100644
--- a/tests/unit/util/logging.t.cpp
+++ b/tests/unit/util/logging.t.cpp
@@ -27,11 +27,13 @@
 
 #include <boost/test/tools/output_test_stream.hpp>
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
 
-NDN_LOG_INIT(ndn.util.tests.Logging);
+using ndn::util::Logger;
+using ndn::util::Logging;
+using ndn::util::LogLevel;
+
+NDN_LOG_INIT(ndn.tests.Logging);
 
 void
 logFromModule1();
@@ -60,7 +62,7 @@
 
 namespace ns1 {
 
-NDN_LOG_INIT(ndn.util.tests.ns1);
+NDN_LOG_INIT(ndn.tests.ns1);
 
 static void
 logFromNamespace1()
@@ -72,7 +74,7 @@
 
 namespace ns2 {
 
-NDN_LOG_INIT(ndn.util.tests.ns2);
+NDN_LOG_INIT(ndn.tests.ns2);
 
 static void
 logFromNamespace2()
@@ -101,7 +103,7 @@
   NDN_LOG_MEMBER_DECL();
 };
 
-NDN_LOG_MEMBER_INIT(ClassWithLogger, ndn.util.tests.ClassWithLogger);
+NDN_LOG_MEMBER_INIT(ClassWithLogger, ndn.tests.ClassWithLogger);
 
 class AbstractClassWithLogger
 {
@@ -123,7 +125,7 @@
 };
 
 // Check that the macro can cope with abstract types
-NDN_LOG_MEMBER_INIT(AbstractClassWithLogger, ndn.util.tests.AbstractClassWithLogger);
+NDN_LOG_MEMBER_INIT(AbstractClassWithLogger, ndn.tests.AbstractClassWithLogger);
 
 class DerivedClass : public AbstractClassWithLogger
 {
@@ -159,13 +161,13 @@
 // but we want to test that the macro expands to well-formed code
 NDN_LOG_MEMBER_DECL_SPECIALIZED((ClassTemplateWithLogger<int, double>));
 
-NDN_LOG_MEMBER_INIT_SPECIALIZED((ClassTemplateWithLogger<int, double>), ndn.util.tests.Specialized1);
-NDN_LOG_MEMBER_INIT_SPECIALIZED((ClassTemplateWithLogger<int, std::string>), ndn.util.tests.Specialized2);
+NDN_LOG_MEMBER_INIT_SPECIALIZED((ClassTemplateWithLogger<int, double>), ndn.tests.Specialized1);
+NDN_LOG_MEMBER_INIT_SPECIALIZED((ClassTemplateWithLogger<int, std::string>), ndn.tests.Specialized2);
 
 constexpr time::microseconds LOG_SYSTIME{1468108800311239LL};
 const std::string LOG_SYSTIME_STR("1468108800.311239");
 
-class LoggingFixture : public ndn::tests::ClockFixture
+class LoggingFixture : public ClockFixture
 {
 protected:
   LoggingFixture()
@@ -202,7 +204,7 @@
   NDN_LOG_TRACE("GetLoggerNames");
   auto names = Logging::getLoggerNames();
   BOOST_CHECK_EQUAL(names.size(), n);
-  BOOST_CHECK_EQUAL(names.count("ndn.util.tests.Logging"), 1);
+  BOOST_CHECK_EQUAL(names.count("ndn.tests.Logging"), 1);
 }
 
 BOOST_AUTO_TEST_SUITE(Severity)
@@ -308,48 +310,48 @@
 
 BOOST_AUTO_TEST_CASE(NamespaceLogger)
 {
-  Logging::setLevel("ndn.util.tests.ns1", LogLevel::INFO);
-  Logging::setLevel("ndn.util.tests.ns2", LogLevel::DEBUG);
+  Logging::setLevel("ndn.tests.ns1", LogLevel::INFO);
+  Logging::setLevel("ndn.tests.ns2", LogLevel::DEBUG);
 
   const auto& levels = Logging::get().getLevels();
   BOOST_CHECK_EQUAL(levels.size(), 2);
-  BOOST_CHECK_EQUAL(levels.at("ndn.util.tests.ns1"), LogLevel::INFO);
-  BOOST_CHECK_EQUAL(levels.at("ndn.util.tests.ns2"), LogLevel::DEBUG);
+  BOOST_CHECK_EQUAL(levels.at("ndn.tests.ns1"), LogLevel::INFO);
+  BOOST_CHECK_EQUAL(levels.at("ndn.tests.ns2"), LogLevel::DEBUG);
 
   const auto& names = Logging::getLoggerNames();
-  BOOST_CHECK_EQUAL(names.count("ndn.util.tests.ns1"), 1);
-  BOOST_CHECK_EQUAL(names.count("ndn.util.tests.ns2"), 1);
+  BOOST_CHECK_EQUAL(names.count("ndn.tests.ns1"), 1);
+  BOOST_CHECK_EQUAL(names.count("ndn.tests.ns2"), 1);
 
   ns1::logFromNamespace1();
   ns2::logFromNamespace2();
 
   Logging::flush();
   BOOST_CHECK(os.is_equal(
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.ns1] hello world from ns1\n" +
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.ns2] hi there from ns2\n"
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.ns1] hello world from ns1\n" +
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.ns2] hi there from ns2\n"
     ));
 }
 
 BOOST_AUTO_TEST_CASE(MemberLogger)
 {
-  Logging::setLevel("ndn.util.tests.ClassWithLogger", LogLevel::INFO);
-  Logging::setLevel("ndn.util.tests.AbstractClassWithLogger", LogLevel::INFO);
-  Logging::setLevel("ndn.util.tests.Specialized1", LogLevel::INFO);
-  // ndn.util.tests.Specialized2 is not enabled
+  Logging::setLevel("ndn.tests.ClassWithLogger", LogLevel::INFO);
+  Logging::setLevel("ndn.tests.AbstractClassWithLogger", LogLevel::INFO);
+  Logging::setLevel("ndn.tests.Specialized1", LogLevel::INFO);
+  // ndn.tests.Specialized2 is not enabled
 
   const auto& names = Logging::getLoggerNames();
-  BOOST_CHECK_EQUAL(names.count("ndn.util.tests.ClassWithLogger"), 1);
-  BOOST_CHECK_EQUAL(names.count("ndn.util.tests.AbstractClassWithLogger"), 1);
-  BOOST_CHECK_EQUAL(names.count("ndn.util.tests.Specialized1"), 1);
-  BOOST_CHECK_EQUAL(names.count("ndn.util.tests.Specialized2"), 1);
+  BOOST_CHECK_EQUAL(names.count("ndn.tests.ClassWithLogger"), 1);
+  BOOST_CHECK_EQUAL(names.count("ndn.tests.AbstractClassWithLogger"), 1);
+  BOOST_CHECK_EQUAL(names.count("ndn.tests.Specialized1"), 1);
+  BOOST_CHECK_EQUAL(names.count("ndn.tests.Specialized2"), 1);
 
   ClassWithLogger::logFromStaticMemberFunction();
   ClassWithLogger{}.logFromConstMemberFunction();
 
   Logging::flush();
   BOOST_CHECK(os.is_equal(
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.ClassWithLogger] static member function\n" +
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.ClassWithLogger] const member function\n"
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.ClassWithLogger] static member function\n" +
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.ClassWithLogger] const member function\n"
     ));
 
   DerivedClass{}.logFromConstMemberFunction();
@@ -357,8 +359,8 @@
 
   Logging::flush();
   BOOST_CHECK(os.is_equal(
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.AbstractClassWithLogger] const member function\n" +
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.AbstractClassWithLogger] overridden virtual function\n"
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.AbstractClassWithLogger] const member function\n" +
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.AbstractClassWithLogger] overridden virtual function\n"
     ));
 
   ClassTemplateWithLogger<int, double>::logFromStaticMemberFunction();
@@ -368,8 +370,8 @@
 
   Logging::flush();
   BOOST_CHECK(os.is_equal(
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.Specialized1] class template static member function\n" +
-    LOG_SYSTIME_STR + "  INFO: [ndn.util.tests.Specialized1] class template non-static member function\n"
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.Specialized1] class template static member function\n" +
+    LOG_SYSTIME_STR + "  INFO: [ndn.tests.Specialized1] class template non-static member function\n"
     ));
 }
 
@@ -702,6 +704,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestLogging
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/notification-stream.t.cpp b/tests/unit/util/notification-stream.t.cpp
index 3ff6ed9..36b9004 100644
--- a/tests/unit/util/notification-stream.t.cpp
+++ b/tests/unit/util/notification-stream.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021 Regents of the University of California,
+ * Copyright (c) 2014-2023 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -32,12 +32,12 @@
 #include "tests/unit/io-key-chain-fixture.hpp"
 #include "tests/unit/util/simple-notification.hpp"
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::util::NotificationStream;
 
 BOOST_AUTO_TEST_SUITE(Util)
-BOOST_FIXTURE_TEST_SUITE(TestNotificationStream, ndn::tests::IoKeyChainFixture)
+BOOST_FIXTURE_TEST_SUITE(TestNotificationStream, IoKeyChainFixture)
 
 BOOST_AUTO_TEST_CASE(Post)
 {
@@ -72,6 +72,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNotificationStream
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/notification-subscriber.t.cpp b/tests/unit/util/notification-subscriber.t.cpp
index 896f632..107784a 100644
--- a/tests/unit/util/notification-subscriber.t.cpp
+++ b/tests/unit/util/notification-subscriber.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022 Regents of the University of California,
+ * Copyright (c) 2014-2023 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -32,11 +32,7 @@
 #include "tests/unit/io-key-chain-fixture.hpp"
 #include "tests/unit/util/simple-notification.hpp"
 
-namespace ndn {
-namespace util {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 class NotificationSubscriberFixture : public IoKeyChainFixture
 {
@@ -131,8 +127,8 @@
   Name streamPrefix;
   DummyClientFace subscriberFace;
   util::NotificationSubscriber<SimpleNotification> subscriber;
-  util::signal::Connection notificationConn;
-  util::signal::Connection nackConn;
+  signal::Connection notificationConn;
+  signal::Connection nackConn;
   uint64_t nextSendNotificationNo;
   uint64_t lastDeliveredSeqNum;
   SimpleNotification lastNotification;
@@ -285,6 +281,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestNotificationSubscriber
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/ostream-joiner.t.cpp b/tests/unit/util/ostream-joiner.t.cpp
index 7e8e63f..2e7ac8f 100644
--- a/tests/unit/util/ostream-joiner.t.cpp
+++ b/tests/unit/util/ostream-joiner.t.cpp
@@ -26,8 +26,7 @@
 #include <numeric>
 #include <boost/test/tools/output_test_stream.hpp>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestOstreamJoiner)
@@ -69,5 +68,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestOstreamJoiner
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/random.t.cpp b/tests/unit/util/random.t.cpp
index 388bb98..b72e754 100644
--- a/tests/unit/util/random.t.cpp
+++ b/tests/unit/util/random.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 #include <array>
 #include <thread>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestRandom)
@@ -125,5 +124,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestRandom
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/regex.t.cpp b/tests/unit/util/regex.t.cpp
index ca15b66..d09688e 100644
--- a/tests/unit/util/regex.t.cpp
+++ b/tests/unit/util/regex.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -32,8 +32,7 @@
 
 #include "tests/boost-test.hpp"
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 using std::string;
 
@@ -490,5 +489,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestRegex
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/rtt-estimator.t.cpp b/tests/unit/util/rtt-estimator.t.cpp
index b819c9b..7070fb0 100644
--- a/tests/unit/util/rtt-estimator.t.cpp
+++ b/tests/unit/util/rtt-estimator.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2016-2019, Regents of the University of California,
+ * Copyright (c) 2016-2023, Regents of the University of California,
  *                          Colorado State University,
  *                          University Pierre & Marie Curie, Sorbonne University.
  *
@@ -27,9 +27,10 @@
 
 #include <cmath>
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::util::RttEstimator;
+using ndn::util::RttEstimatorWithStats;
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestRttEstimator)
@@ -168,6 +169,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestRttEstimator
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/scheduler.t.cpp b/tests/unit/util/scheduler.t.cpp
index 1040b92..e5c99e5 100644
--- a/tests/unit/util/scheduler.t.cpp
+++ b/tests/unit/util/scheduler.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,11 +26,11 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace ndn {
-namespace scheduler {
-namespace tests {
+namespace ndn::tests {
 
-class SchedulerFixture : public ndn::tests::IoFixture
+using namespace ndn::scheduler;
+
+class SchedulerFixture : public IoFixture
 {
 protected:
   Scheduler scheduler{m_io};
@@ -383,6 +383,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestScheduler
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace scheduler
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/segment-fetcher.t.cpp b/tests/unit/util/segment-fetcher.t.cpp
index 4abe243..1166110 100644
--- a/tests/unit/util/segment-fetcher.t.cpp
+++ b/tests/unit/util/segment-fetcher.t.cpp
@@ -31,11 +31,7 @@
 
 #include <set>
 
-namespace ndn {
-namespace util {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 class SegmentFetcherFixture : public IoKeyChainFixture
 {
@@ -853,6 +849,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSegmentFetcher
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/segmenter.t.cpp b/tests/unit/util/segmenter.t.cpp
index d7ab98a..f6eb2a8 100644
--- a/tests/unit/util/segmenter.t.cpp
+++ b/tests/unit/util/segmenter.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,11 +24,7 @@
 #include "tests/boost-test.hpp"
 #include "tests/key-chain-fixture.hpp"
 
-namespace ndn {
-namespace util {
-namespace tests {
-
-using namespace ndn::tests;
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_FIXTURE_TEST_SUITE(TestSegmenter, KeyChainFixture)
@@ -144,6 +140,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSegmenter
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/sha256.t.cpp b/tests/unit/util/sha256.t.cpp
index c5fd1fd..4a31ac7 100644
--- a/tests/unit/util/sha256.t.cpp
+++ b/tests/unit/util/sha256.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,9 @@
 #include <boost/endian/conversion.hpp>
 #include <sstream>
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::util::Sha256;
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestSha256)
@@ -201,6 +201,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSha256
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/signal.t.cpp b/tests/unit/util/signal.t.cpp
index b3640f9..001d02a 100644
--- a/tests/unit/util/signal.t.cpp
+++ b/tests/unit/util/signal.t.cpp
@@ -25,10 +25,9 @@
 
 #include <boost/concept_check.hpp>
 
-namespace ndn {
-namespace util {
-namespace signal {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::signal;
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestSignal)
@@ -477,7 +476,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSignal
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace signal
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/simple-notification.hpp b/tests/unit/util/simple-notification.hpp
index ece2c48..239574b 100644
--- a/tests/unit/util/simple-notification.hpp
+++ b/tests/unit/util/simple-notification.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022 Regents of the University of California,
+ * Copyright (c) 2014-2023 Regents of the University of California,
  *                         Arizona Board of Regents,
  *                         Colorado State University,
  *                         University Pierre & Marie Curie, Sorbonne University,
@@ -30,9 +30,7 @@
 
 #include "ndn-cxx/encoding/block-helpers.hpp"
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
 
 class SimpleNotification
 {
@@ -82,8 +80,6 @@
   std::string m_message;
 };
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
 
 #endif // NDN_CXX_TESTS_UNIT_UTIL_SIMPLE_NOTIFICATION_HPP
diff --git a/tests/unit/util/sqlite3-statement.t.cpp b/tests/unit/util/sqlite3-statement.t.cpp
index 99ea89f..b3d32d5 100644
--- a/tests/unit/util/sqlite3-statement.t.cpp
+++ b/tests/unit/util/sqlite3-statement.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,9 +27,9 @@
 #include <cstring>
 #include <sqlite3.h>
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::util::Sqlite3Statement;
 
 class Sqlite3DbFixture
 {
@@ -153,6 +153,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestSqlite3Statement
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/string-helper.t.cpp b/tests/unit/util/string-helper.t.cpp
index 3816fab..9361ed6 100644
--- a/tests/unit/util/string-helper.t.cpp
+++ b/tests/unit/util/string-helper.t.cpp
@@ -28,9 +28,7 @@
 #include <cstring>
 #include <boost/test/tools/output_test_stream.hpp>
 
-namespace ndn {
-namespace util {
-namespace tests {
+namespace ndn::tests {
 
 using boost::test_tools::output_test_stream;
 
@@ -202,6 +200,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestStringHelper
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace util
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/time-unit-test-clock.t.cpp b/tests/unit/util/time-unit-test-clock.t.cpp
index f1be623..6b34ff8 100644
--- a/tests/unit/util/time-unit-test-clock.t.cpp
+++ b/tests/unit/util/time-unit-test-clock.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2020 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 #include <boost/lexical_cast.hpp>
 #include <thread>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_FIXTURE_TEST_SUITE(TestTimeUnitTestClock, ClockFixture)
@@ -51,8 +50,7 @@
   BOOST_CHECK_GT(time::system_clock::now().time_since_epoch(),
                  time::UnitTestClockTraits<time::system_clock>::getDefaultStartTime());
 
-  time::system_clock::TimePoint referenceTime =
-    time::fromUnixTimestamp(time::milliseconds(1390966967032LL));
+  auto referenceTime = time::fromUnixTimestamp(time::milliseconds(1390966967032LL));
   BOOST_CHECK_GT(time::system_clock::now(), referenceTime);
 
   m_systemClock->setNow(referenceTime.time_since_epoch());
@@ -134,5 +132,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestTimeUnitTestClock
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/util/time.t.cpp b/tests/unit/util/time.t.cpp
index 2232e12..9004700 100644
--- a/tests/unit/util/time.t.cpp
+++ b/tests/unit/util/time.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,9 +26,9 @@
 #include <boost/lexical_cast.hpp>
 #include <thread>
 
-namespace ndn {
-namespace time {
-namespace tests {
+namespace ndn::tests {
+
+using namespace ndn::time;
 
 BOOST_AUTO_TEST_SUITE(Util)
 BOOST_AUTO_TEST_SUITE(TestTime)
@@ -170,6 +170,4 @@
 BOOST_AUTO_TEST_SUITE_END() // TestTime
 BOOST_AUTO_TEST_SUITE_END() // Util
 
-} // namespace tests
-} // namespace time
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tests/unit/version.t.cpp b/tests/unit/version.t.cpp
index ff3e32a..527bc95 100644
--- a/tests/unit/version.t.cpp
+++ b/tests/unit/version.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 
 #include <cstdio>
 
-namespace ndn {
-namespace tests {
+namespace ndn::tests {
 
 BOOST_AUTO_TEST_SUITE(TestVersion)
 
@@ -58,5 +57,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestVersion
 
-} // namespace tests
-} // namespace ndn
+} // namespace ndn::tests
diff --git a/tools/ndnsec/accumulator.hpp b/tools/ndnsec/accumulator.hpp
index a696000..eec3e09 100644
--- a/tools/ndnsec/accumulator.hpp
+++ b/tools/ndnsec/accumulator.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include <boost/program_options/value_semantic.hpp>
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 /**
  * @brief An accumulating option value to handle multiple incrementing options.
@@ -154,7 +153,6 @@
   return new AccumulatorType<T>(store);
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
 
 #endif // NDN_CXX_TOOLS_NDNSEC_ACCUMULATOR_HPP
diff --git a/tools/ndnsec/cert-dump.cpp b/tools/ndnsec/cert-dump.cpp
index b5ac12f..8237f5d 100644
--- a/tools/ndnsec/cert-dump.cpp
+++ b/tools/ndnsec/cert-dump.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include <boost/date_time/posix_time/posix_time_duration.hpp>
 #endif // BOOST_VERSION < 106700
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_cert_dump(int argc, char** argv)
@@ -142,5 +141,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/cert-gen.cpp b/tools/ndnsec/cert-gen.cpp
index c151471..c382119 100644
--- a/tools/ndnsec/cert-gen.cpp
+++ b/tools/ndnsec/cert-gen.cpp
@@ -27,8 +27,7 @@
 #include "ndn-cxx/security/transform/buffer-source.hpp"
 #include "ndn-cxx/security/transform/stream-sink.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_cert_gen(int argc, char** argv)
@@ -157,5 +156,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/cert-install.cpp b/tools/ndnsec/cert-install.cpp
index 9a13e33..345ee24 100644
--- a/tools/ndnsec/cert-install.cpp
+++ b/tools/ndnsec/cert-install.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -27,8 +27,7 @@
 #include "ndn-cxx/security/transform/stream-sink.hpp"
 #include "ndn-cxx/security/transform/stream-source.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_cert_install(int argc, char** argv)
@@ -120,5 +119,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/delete.cpp b/tools/ndnsec/delete.cpp
index 2159bb3..25de41c 100644
--- a/tools/ndnsec/delete.cpp
+++ b/tools/ndnsec/delete.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,8 +22,7 @@
 #include "ndnsec.hpp"
 #include "util.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_delete(int argc, char** argv)
@@ -112,5 +111,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/export.cpp b/tools/ndnsec/export.cpp
index 4ce0ebc..5641e08 100644
--- a/tools/ndnsec/export.cpp
+++ b/tools/ndnsec/export.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,8 +26,7 @@
 
 #include <openssl/crypto.h>
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_export(int argc, char** argv)
@@ -131,5 +130,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/get-default.cpp b/tools/ndnsec/get-default.cpp
index 37f7425..8dba1bf 100644
--- a/tools/ndnsec/get-default.cpp
+++ b/tools/ndnsec/get-default.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,8 +22,7 @@
 #include "ndnsec.hpp"
 #include "util.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_get_default(int argc, char** argv)
@@ -127,5 +126,4 @@
   }
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/import.cpp b/tools/ndnsec/import.cpp
index c25b0c7..9e0c830 100644
--- a/tools/ndnsec/import.cpp
+++ b/tools/ndnsec/import.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,8 +26,7 @@
 
 #include <openssl/crypto.h>
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_import(int argc, char** argv)
@@ -92,5 +91,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/key-gen.cpp b/tools/ndnsec/key-gen.cpp
index ac85fe8..a045cd6 100644
--- a/tools/ndnsec/key-gen.cpp
+++ b/tools/ndnsec/key-gen.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,8 +22,7 @@
 #include "ndnsec.hpp"
 #include "util.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_key_gen(int argc, char** argv)
@@ -158,5 +157,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/list.cpp b/tools/ndnsec/list.cpp
index 502d909..3b02b80 100644
--- a/tools/ndnsec/list.cpp
+++ b/tools/ndnsec/list.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 
 #include "ndn-cxx/util/indented-stream.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 namespace {
 
 // https://en.wikipedia.org/wiki/Box_Drawing
@@ -247,5 +246,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/main.cpp b/tools/ndnsec/main.cpp
index 436388f..7609345 100644
--- a/tools/ndnsec/main.cpp
+++ b/tools/ndnsec/main.cpp
@@ -31,7 +31,7 @@
 
 NDN_LOG_INIT(ndnsec);
 
-const char NDNSEC_HELP_TEXT[] = R"STR(Usage: ndnsec COMMAND [OPTION]...
+constexpr std::string_view NDNSEC_HELP_TEXT = R"STR(Usage: ndnsec COMMAND [OPTION]...
 
 Available commands:
   help           Print this help text
@@ -49,7 +49,8 @@
   import         Import an identity from a SafeBag
   unlock-tpm     Unlock the TPM
 
-Try 'ndnsec COMMAND --help' for more information on each command.)STR";
+Try 'ndnsec COMMAND --help' for more information on a command.
+)STR";
 
 int
 main(int argc, char* argv[])
@@ -66,7 +67,7 @@
     argv++;
   }
   else {
-    std::cerr << NDNSEC_HELP_TEXT << std::endl;
+    std::cerr << NDNSEC_HELP_TEXT;
     return 2;
   }
 
@@ -74,7 +75,7 @@
 
   try {
     using namespace ndn::ndnsec;
-    if (command == "help")              { std::cout << NDNSEC_HELP_TEXT << std::endl; }
+    if (command == "help")              { std::cout << NDNSEC_HELP_TEXT; }
     else if (command == "version")      { std::cout << NDN_CXX_VERSION_BUILD_STRING << std::endl; }
     else if (command == "list")         { return ndnsec_list(argc, argv); }
     else if (command == "get-default")  { return ndnsec_get_default(argc, argv); }
@@ -89,9 +90,7 @@
     else if (command == "import")       { return ndnsec_import(argc, argv); }
     else if (command == "unlock-tpm")   { return ndnsec_unlock_tpm(argc, argv); }
     else {
-      std::cerr << "ERROR: Unknown command '" << command << "'\n"
-                << "\n"
-                << NDNSEC_HELP_TEXT << std::endl;
+      std::cerr << "ERROR: Unknown command '" << command << "'\n\n" << NDNSEC_HELP_TEXT;
       return 2;
     }
   }
diff --git a/tools/ndnsec/ndnsec.hpp b/tools/ndnsec/ndnsec.hpp
index bb773ea..49c4de8 100644
--- a/tools/ndnsec/ndnsec.hpp
+++ b/tools/ndnsec/ndnsec.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,8 +22,7 @@
 #ifndef NDN_CXX_TOOLS_NDNSEC_NDNSEC_HPP
 #define NDN_CXX_TOOLS_NDNSEC_NDNSEC_HPP
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 // TODO: convert to tool registry (maybe)
 
@@ -63,7 +62,6 @@
 int
 ndnsec_unlock_tpm(int argc, char** argv);
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
 
 #endif // NDN_CXX_TOOLS_NDNSEC_NDNSEC_HPP
diff --git a/tools/ndnsec/set-default.cpp b/tools/ndnsec/set-default.cpp
index 128ae19..b0ebf09 100644
--- a/tools/ndnsec/set-default.cpp
+++ b/tools/ndnsec/set-default.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -22,8 +22,7 @@
 #include "ndnsec.hpp"
 #include "util.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_set_default(int argc, char** argv)
@@ -95,5 +94,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/sign-req.cpp b/tools/ndnsec/sign-req.cpp
index e202bc5..ca53819 100644
--- a/tools/ndnsec/sign-req.cpp
+++ b/tools/ndnsec/sign-req.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -24,8 +24,7 @@
 
 #include "ndn-cxx/security/signing-helpers.hpp"
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_sign_req(int argc, char** argv)
@@ -93,5 +92,4 @@
   return 0;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/unlock-tpm.cpp b/tools/ndnsec/unlock-tpm.cpp
index 1baaa55..97cd702 100644
--- a/tools/ndnsec/unlock-tpm.cpp
+++ b/tools/ndnsec/unlock-tpm.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -28,8 +28,7 @@
 #include <cstring>
 #include <unistd.h>
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 int
 ndnsec_unlock_tpm(int argc, char** argv)
@@ -86,5 +85,4 @@
 #endif // NDN_CXX_HAVE_GETPASS
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/util.cpp b/tools/ndnsec/util.cpp
index ae407db..a85b9e3 100644
--- a/tools/ndnsec/util.cpp
+++ b/tools/ndnsec/util.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2022 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,7 @@
 
 #include <unistd.h>
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 bool
 getPassword(std::string& password, const std::string& prompt, bool shouldConfirm)
@@ -89,5 +88,4 @@
   NDN_CXX_UNREACHABLE;
 }
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
diff --git a/tools/ndnsec/util.hpp b/tools/ndnsec/util.hpp
index 913198c..7a244d5 100644
--- a/tools/ndnsec/util.hpp
+++ b/tools/ndnsec/util.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2021 Regents of the University of California.
+ * Copyright (c) 2013-2023 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -31,8 +31,7 @@
 #include <boost/program_options/parsers.hpp>
 #include <boost/program_options/variables_map.hpp>
 
-namespace ndn {
-namespace ndnsec {
+namespace ndn::ndnsec {
 
 /**
  * @brief Get certificate of given name from PIB.
@@ -77,7 +76,6 @@
 bool
 getPassword(std::string& password, const std::string& prompt, bool shouldConfirm = true);
 
-} // namespace ndnsec
-} // namespace ndn
+} // namespace ndn::ndnsec
 
 #endif // NDN_CXX_TOOLS_NDNSEC_UTIL_HPP