diff --git a/src/security/v2/additional-description.hpp b/src/security/v2/additional-description.hpp
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+++ b/src/security/v2/additional-description.hpp
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+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2016 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.
+ */
+
+#ifndef NDN_SECURITY_V2_ADDITIONAL_DESCRIPTION_HPP
+#define NDN_SECURITY_V2_ADDITIONAL_DESCRIPTION_HPP
+
+#include "../../common.hpp"
+#include "../../encoding/tlv.hpp"
+#include "../../encoding/block.hpp"
+#include <map>
+
+namespace ndn {
+namespace security {
+namespace v2 {
+
+/**
+ * @brief Abstraction of AdditionalDescription
+ * @sa docs/tutorials/certificate-format.rst
+ */
+class AdditionalDescription
+{
+public:
+  class Error : public tlv::Error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : tlv::Error(what)
+    {
+    }
+  };
+
+  typedef std::map<std::string, std::string>::iterator iterator;
+  typedef std::map<std::string, std::string>::const_iterator const_iterator;
+
+public:
+
+  /**
+   * @brief Create an empty AdditionalDescription
+   */
+  AdditionalDescription() = default;
+
+  /**
+   * @brief Create AdditionalDescription from @p block
+   */
+  explicit
+  AdditionalDescription(const Block& block);
+
+  const std::string&
+  get(const std::string& key) const;
+
+  void
+  set(const std::string& key, const std::string& value);
+
+  bool
+  has(const std::string& key) const;
+
+  size_t
+  size() const
+  {
+    return m_info.size();
+  }
+
+  iterator
+  begin();
+
+  iterator
+  end();
+
+  const_iterator
+  begin() const;
+
+  const_iterator
+  end() const;
+
+  /** @brief Fast encoding or block size estimation
+   */
+  template<encoding::Tag TAG>
+  size_t
+  wireEncode(EncodingImpl<TAG>& encoder) const;
+
+  /** @brief Encode ValidityPeriod into TLV block
+   */
+  const Block&
+  wireEncode() const;
+
+  /** @brief Decode ValidityPeriod from TLV block
+   *  @throw Error when an invalid TLV block supplied
+   */
+  void
+  wireDecode(const Block& wire);
+
+public: // EqualityComparable concept
+
+  bool
+  operator==(const AdditionalDescription& other) const;
+
+  bool
+  operator!=(const AdditionalDescription& other) const;
+
+private:
+
+  std::map<std::string, std::string> m_info;
+
+  mutable Block m_wire;
+};
+
+std::ostream&
+operator<<(std::ostream& os, const AdditionalDescription& period);
+
+} // namespace v2
+
+using v2::AdditionalDescription;
+
+} // namespace security
+} // namespace ndn
+
+#endif // NDN_SECURITY_V2_ADDITIONAL_DESCRIPTION_HPP