security: Add wrapper for public/private key in transformation

Change-Id: I6610cccc8bb20b4e9e227895cf24b595a6e13698
Refs: #3009, #3010
diff --git a/src/security/transform/public-key.hpp b/src/security/transform/public-key.hpp
new file mode 100644
index 0000000..169b9e0
--- /dev/null
+++ b/src/security/transform/public-key.hpp
@@ -0,0 +1,137 @@
+/* -*- 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_CXX_SECURITY_TRANSFORM_PUBLIC_KEY_HPP
+#define NDN_CXX_SECURITY_TRANSFORM_PUBLIC_KEY_HPP
+
+#include "../security-common.hpp"
+#include "../../encoding/buffer.hpp"
+
+namespace ndn {
+namespace security {
+namespace transform {
+
+class VerifierFilter;
+
+/**
+ * @brief Abstraction of public key in crypto transformation
+ */
+class PublicKey : noncopyable
+{
+public:
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : std::runtime_error(what)
+    {
+    }
+  };
+
+  friend class VerifierFilter;
+
+public:
+  /**
+   * @brief Create a public key instance
+   *
+   * One must call loadXXXX(...) to load public key.
+   */
+  PublicKey();
+
+  ~PublicKey();
+
+  /**
+   * @brief Get the type of the public key
+   */
+  KeyType
+  getKeyType() const;
+
+  /**
+   * @brief Load the public key in PKCS#8 format from a buffer @p buf
+   */
+  void
+  loadPkcs8(const uint8_t* buf, size_t size);
+
+  /**
+   * @brief Load the public key in PKCS#8 format from a stream @p is
+   */
+  void
+  loadPkcs8(std::istream& is);
+
+  /**
+   * @brief Load the public key in base64-encoded PKCS#8 format from a buffer @p buf
+   */
+  void
+  loadPkcs8Base64(const uint8_t* buf, size_t size);
+
+  /**
+   * @brief Load the public key in base64-encoded PKCS#8 format from a stream @p is
+   */
+  void
+  loadPkcs8Base64(std::istream& is);
+
+  /**
+   * @brief Save the public key in PKCS#8 format into a stream @p os
+   */
+  void
+  savePkcs8(std::ostream& os) const;
+
+  /**
+   * @brief Save the public key in base64-encoded PKCS#8 format into a stream @p os
+   */
+  void
+  savePkcs8Base64(std::ostream& os) const;
+
+  /**
+   * @return Cipher text of @p plainText encrypted using the public key.
+   *
+   * Only RSA encryption is supported for now.
+   */
+  ConstBufferPtr
+  encrypt(const uint8_t* plainText, size_t plainLen) const;
+
+private:
+  /**
+   * @return A pointer to an EVP_PKEY instance.
+   *
+   * One need to explicitly cast the return value to EVP_PKEY*.
+   */
+  void*
+  getEvpPkey() const;
+
+private:
+  ConstBufferPtr
+  toPkcs8() const;
+
+  ConstBufferPtr
+  rsaEncrypt(const uint8_t* plainText, size_t plainLen) const;
+
+private:
+  class Impl;
+  unique_ptr<Impl> m_impl;
+};
+
+} // namespace transform
+} // namespace security
+} // namespace ndn
+
+#endif // NDN_CXX_SECURITY_TRANSFORM_PUBLIC_KEY_HPP