security: Add transformation sink/source

Change-Id: I2698f79f639c2bd7c3ce2e00f48be634dc4c983d
Refs: #3009
diff --git a/src/security/transform/stream-source.hpp b/src/security/transform/stream-source.hpp
new file mode 100644
index 0000000..b818fe7
--- /dev/null
+++ b/src/security/transform/stream-source.hpp
@@ -0,0 +1,69 @@
+/* -*- 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_STREAM_SOURCE_HPP
+#define NDN_CXX_SECURITY_TRANSFORM_STREAM_SOURCE_HPP
+
+#include "transform-base.hpp"
+#include <iostream>
+
+namespace ndn {
+namespace security {
+namespace transform {
+
+/**
+ * @brief A source taking an std::istream as input
+ */
+class StreamSource : public Source
+{
+public:
+  /**
+   * @brief Construst a source using @p is as input.
+   *
+   * @param is The input stream
+   * @param bufLen The internal buffer size. The default size is 1024.
+   * @pre bufLen must be larger than 0.
+   */
+  explicit
+  StreamSource(std::istream& is, size_t bufLen = DEFAULT_BUFFER_LEN);
+
+private:
+  /**
+   * @brief Read bytes from the input stream until EOF is reached and write them into the next module.
+   */
+  virtual void
+  doPump() final;
+
+public:
+  static const std::size_t DEFAULT_BUFFER_LEN;
+
+private:
+  std::istream& m_is;
+  size_t m_bufferSize;
+};
+
+typedef StreamSource streamSource;
+
+} // namespace transform
+} // namespace security
+} // namespace ndn
+
+#endif // NDN_CXX_SECURITY_TRANSFORM_STREAM_SOURCE_HPP