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/src/security/tpm/back-end-mem.cpp b/src/security/tpm/back-end-mem.cpp
new file mode 100644
index 0000000..beac9db
--- /dev/null
+++ b/src/security/tpm/back-end-mem.cpp
@@ -0,0 +1,103 @@
+/* -*- 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.
+ */
+
+#include "back-end-mem.hpp"
+#include "key-handle-mem.hpp"
+#include "../transform/private-key.hpp"
+#include "../../encoding/buffer-stream.hpp"
+#include <unordered_map>
+
+namespace ndn {
+namespace security {
+namespace tpm {
+
+using transform::PrivateKey;
+
+class BackEndMem::Impl
+{
+public:
+  std::unordered_map<Name, shared_ptr<PrivateKey>> keys;
+};
+
+BackEndMem::BackEndMem()
+  : m_impl(new Impl)
+{
+}
+
+BackEndMem::~BackEndMem() = default;
+
+bool
+BackEndMem::doHasKey(const Name& keyName) const
+{
+  return (m_impl->keys.count(keyName) > 0);
+}
+
+unique_ptr<KeyHandle>
+BackEndMem::doGetKeyHandle(const Name& keyName) const
+{
+  auto it = m_impl->keys.find(keyName);
+  if (it == m_impl->keys.end())
+    return nullptr;
+  return make_unique<KeyHandleMem>(it->second);
+}
+
+unique_ptr<KeyHandle>
+BackEndMem::doCreateKey(const Name& identityName, const KeyParams& params)
+{
+  shared_ptr<PrivateKey> key(transform::generatePrivateKey(params).release());
+  unique_ptr<KeyHandle> keyHandle = make_unique<KeyHandleMem>(key);
+
+  setKeyName(*keyHandle, identityName, params);
+
+  m_impl->keys[keyHandle->getKeyName()] = key;
+  return keyHandle;
+}
+
+void
+BackEndMem::doDeleteKey(const Name& keyName)
+{
+  m_impl->keys.erase(keyName);
+}
+
+ConstBufferPtr
+BackEndMem::doExportKey(const Name& keyName, const char* pw, size_t pwLen)
+{
+  OBufferStream os;
+  m_impl->keys[keyName]->savePkcs8(os, pw, pwLen);
+  return os.buf();
+}
+
+void
+BackEndMem::doImportKey(const Name& keyName, const uint8_t* buf, size_t size, const char* pw, size_t pwLen)
+{
+  try {
+    auto key = make_shared<PrivateKey>();
+    key->loadPkcs8(buf, size, pw, pwLen);
+    m_impl->keys[keyName] = key;
+  }
+  catch (const PrivateKey::Error& e) {
+    BOOST_THROW_EXCEPTION(Error(std::string("Cannot import private key: ") + e.what()));
+  }
+}
+
+} // namespace tpm
+} // namespace security
+} // namespace ndn