diff --git a/src/security/transform/stream-source.cpp b/src/security/transform/stream-source.cpp
new file mode 100644
index 0000000..5248646
--- /dev/null
+++ b/src/security/transform/stream-source.cpp
@@ -0,0 +1,70 @@
+/* -*- 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 "stream-source.hpp"
+#include <vector>
+
+namespace ndn {
+namespace security {
+namespace transform {
+
+const std::size_t StreamSource::DEFAULT_BUFFER_LEN = 1024;
+
+StreamSource::StreamSource(std::istream& is, size_t bufferSize)
+  : Source()
+  , m_is(is)
+  , m_bufferSize(bufferSize)
+{
+  BOOST_ASSERT(bufferSize > 0);
+}
+
+void
+StreamSource::doPump()
+{
+  BOOST_ASSERT(m_next != nullptr);
+
+  std::vector<uint8_t> buffer(m_bufferSize);
+  size_t dataOffset = 0;
+  size_t dataLen = 0;
+
+  while (dataLen > 0 || !m_is.eof()) {
+    if (dataLen > 0) {
+      // we have some leftover, handle them first
+      size_t nBytesWritten = m_next->write(&buffer[dataOffset], dataLen);
+
+      dataOffset += nBytesWritten;
+      dataLen -= nBytesWritten;
+    }
+    else if (m_is.bad()) {
+      BOOST_THROW_EXCEPTION(Error(getIndex(), "Input stream in bad state"));
+    }
+    else if (m_is.good()) {
+      m_is.read(reinterpret_cast<char*>(&buffer.front()), buffer.size());
+      dataOffset = 0;
+      dataLen = m_is.gcount();
+    }
+  }
+  m_next->end();
+}
+
+} // namespace transform
+} // namespace security
+} // namespace ndn