security: Reorganizing source code to prepare for support of two version of NDN certificates

This commit also removes unused ndn_digestSha256 function and deprecates
crypto::sha256 in favor of crypto::computeSha256Digest in util/crypto.hpp.

Change-Id: I24ee50ff073a96b868633bdf2cfade412d3605f3
Refs: #3098
diff --git a/src/security/v1/certificate.hpp b/src/security/v1/certificate.hpp
new file mode 100644
index 0000000..f2f70bf
--- /dev/null
+++ b/src/security/v1/certificate.hpp
@@ -0,0 +1,226 @@
+/* -*- 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.
+ *
+ * @author Yingdi Yu <http://irl.cs.ucla.edu/~yingdi/>
+ * @author Jeff Thompson <jefft0@remap.ucla.edu>
+ * @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
+ */
+
+#ifndef NDN_SECURITY_V1_CERTIFICATE_HPP
+#define NDN_SECURITY_V1_CERTIFICATE_HPP
+
+#include "../../common.hpp"
+#include "../../data.hpp"
+#include "certificate-subject-description.hpp"
+#include "certificate-extension.hpp"
+#include "public-key.hpp"
+
+namespace ndn {
+namespace security {
+namespace v1 {
+
+class Certificate : public Data
+{
+public:
+  class Error : public Data::Error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : Data::Error(what)
+    {
+    }
+  };
+
+  typedef std::vector<CertificateSubjectDescription> SubjectDescriptionList;
+  typedef std::vector<CertificateExtension> ExtensionList;
+
+  /**
+   * @brief The default constructor.
+   */
+  Certificate();
+
+  /**
+   * @brief Create a Certificate from the content in the data packet.
+   * @param data The data packet with the content to decode.
+   */
+  explicit
+  Certificate(const Data& data);
+
+  /**
+   * @brief Create a Certificate from the a block
+   * @param block The raw block of the certificate
+   */
+  explicit
+  Certificate(const Block& block);
+
+  virtual
+  ~Certificate();
+
+  void
+  wireDecode(const Block& wire);
+
+  /**
+   * @brief encode certificate info into content
+   */
+  void
+  encode();
+
+  /**
+   * @brief Add a subject description.
+   * @param description The description to be added.
+   */
+  void
+  addSubjectDescription(const CertificateSubjectDescription& description)
+  {
+    m_subjectDescriptionList.push_back(description);
+  }
+
+  const SubjectDescriptionList&
+  getSubjectDescriptionList() const
+  {
+    return m_subjectDescriptionList;
+  }
+
+  SubjectDescriptionList&
+  getSubjectDescriptionList()
+  {
+    return m_subjectDescriptionList;
+  }
+
+  /**
+   * @brief Add a certificate extension.
+   * @param extension the extension to be added
+   */
+  void
+  addExtension(const CertificateExtension& extension)
+  {
+    m_extensionList.push_back(extension);
+  }
+
+  const ExtensionList&
+  getExtensionList() const
+  {
+    return m_extensionList;
+  }
+
+  ExtensionList&
+  getExtensionList()
+  {
+    return m_extensionList;
+  }
+
+  void
+  setNotBefore(const time::system_clock::TimePoint& notBefore)
+  {
+    m_notBefore = notBefore;
+  }
+
+  time::system_clock::TimePoint&
+  getNotBefore()
+  {
+    return m_notBefore;
+  }
+
+  const time::system_clock::TimePoint&
+  getNotBefore() const
+  {
+    return m_notBefore;
+  }
+
+  void
+  setNotAfter(const time::system_clock::TimePoint& notAfter)
+  {
+    m_notAfter = notAfter;
+  }
+
+  time::system_clock::TimePoint&
+  getNotAfter()
+  {
+    return m_notAfter;
+  }
+
+  const time::system_clock::TimePoint&
+  getNotAfter() const
+  {
+    return m_notAfter;
+  }
+
+  void
+  setPublicKeyInfo(const PublicKey& key)
+  {
+    m_key = key;
+  }
+
+  PublicKey&
+  getPublicKeyInfo()
+  {
+    return m_key;
+  }
+
+  const PublicKey&
+  getPublicKeyInfo() const
+  {
+    return m_key;
+  }
+
+  /**
+   * @brief Check if the certificate is valid.
+   * @return True if the current time is earlier than notBefore.
+   */
+  bool
+  isTooEarly();
+
+  /**
+   * @brief Check if the certificate is valid.
+   * @return True if the current time is later than notAfter.
+   */
+  bool
+  isTooLate();
+
+  void
+  printCertificate(std::ostream& os, const std::string& indent = "") const;
+
+protected:
+  void
+  decode();
+
+protected:
+  SubjectDescriptionList m_subjectDescriptionList;
+  time::system_clock::TimePoint m_notBefore;
+  time::system_clock::TimePoint m_notAfter;
+  PublicKey m_key;
+  ExtensionList m_extensionList;
+};
+
+std::ostream&
+operator<<(std::ostream& os, const Certificate& cert);
+
+} // namespace v1
+} // namespace security
+
+#ifdef NDN_CXX_KEEP_SECURITY_V1_ALIASES
+/// @deprecated When needed, use explicit namespace
+using security::v1::Certificate;
+#endif // NDN_CXX_KEEP_SECURITY_V1_ALIASES
+
+} // namespace ndn
+
+#endif // NDN_SECURITY_V1_CERTIFICATE_HPP