security: Add new TPM framework

The TPM framework is separated into two parts:
1) The front end class Tpm provides the interface to KeyChain. The public
   interface of Tpm is read-only.
2) The back end classes represent concrete implementations, such as
   tpm::BackEndFile and tpm::BackEndOsx which may also provide
   implementation-specific management interfaces.

New TPM supports different key id type when generating new key.  The
default type is changed to 64-bit random number.

Change-Id: I41154c2ded4b65fb0bef2f4a0d2c5b77843be05d
Refs: #2948
diff --git a/tests/unit-tests/security/tpm/back-end-wrapper-osx.hpp b/tests/unit-tests/security/tpm/back-end-wrapper-osx.hpp
new file mode 100644
index 0000000..d02b717
--- /dev/null
+++ b/tests/unit-tests/security/tpm/back-end-wrapper-osx.hpp
@@ -0,0 +1,87 @@
+/* -*- 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_TESTS_SECURITY_TPM_BACK_END_WRAPPER_OSX_HPP
+#define NDN_TESTS_SECURITY_TPM_BACK_END_WRAPPER_OSX_HPP
+
+#include "security/tpm/back-end-osx.hpp"
+#include "security/tpm/key-handle-osx.hpp"
+#include <Availability.h>
+
+namespace ndn {
+namespace security {
+namespace tpm {
+namespace tests {
+
+/**
+ * @brief A wrapper of tpm::BackEndOsx for unit test template.
+ */
+class BackEndWrapperOsx
+{
+public:
+  BackEndWrapperOsx()
+  {
+    std::string oldHOME;
+    if (std::getenv("OLD_HOME"))
+      oldHOME = std::getenv("OLD_HOME");
+
+    if (std::getenv("HOME"))
+      m_HOME = std::getenv("HOME");
+
+    if (!oldHOME.empty())
+      setenv("HOME", oldHOME.c_str(), 1);
+    else
+      unsetenv("HOME");
+
+    m_impl = unique_ptr<BackEnd>(new BackEndOsx);
+  }
+
+  ~BackEndWrapperOsx()
+  {
+    if (!m_HOME.empty())
+      setenv("HOME", m_HOME.c_str(), 1);
+    else
+      unsetenv("HOME");
+  }
+
+  BackEnd&
+  getTpm()
+  {
+    return *m_impl;
+  }
+
+  std::string
+  getScheme()
+  {
+    return "tpm-osxkeychain";
+  }
+
+private:
+  std::string m_HOME;
+  unique_ptr<BackEnd> m_impl;
+};
+
+} // namespace tests
+} // namespace tpm
+} // namespace security
+} // namespace ndn
+
+#endif // NDN_TESTS_SECURITY_TPM_BACK_END_WRAPPER_OSX_HPP