diff --git a/core/intermediate-node.cpp b/core/intermediate-node.cpp
new file mode 100644
index 0000000..11c37ff
--- /dev/null
+++ b/core/intermediate-node.cpp
@@ -0,0 +1,72 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014,  Regents of the University of California
+ *
+ * This file is part of NSL (NDN Signature Logger).
+ * See AUTHORS.md for complete list of NSL authors and contributors.
+ *
+ * NSL is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NSL 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NSL, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @author Peizhen Guo <patrick.guopz@gmail.com>
+ */
+#include "intermediate-node.hpp"
+
+namespace nsl {
+
+bool
+IntermediateNode::isFull() const
+{
+  return m_isFull;
+}
+
+
+
+bool
+IntermediateNode::setIsFull(uint64_t number)
+{
+  Index info = this->getIndex();
+  uint64_t num = info.number;
+  uint64_t lev = info.level;
+  if (double(num) + pow(2, lev) <= number)
+    {
+      m_isFull = true;
+      return m_isFull;
+    }
+  else
+    {
+      m_isFull = false;
+      return m_isFull;
+    }
+
+}
+
+
+
+void
+IntermediateNode::computeHash(ndn::ConstBufferPtr hash_l, ndn::ConstBufferPtr hash_r)
+{
+  ndn::Buffer tmp_buf = *hash_l;
+  for (int i = 0; i < hash_r->size(); i++)
+    {
+      tmp_buf.push_back((*hash_r)[i]);
+    }
+  ndn::ConstBufferPtr digest = ndn::crypto::sha256(tmp_buf.buf(), tmp_buf.size());
+  this->setHash(digest);
+}
+
+void IntermediateNode::computeHashOneSide(ndn::ConstBufferPtr hash_l)
+{
+  ndn::ConstBufferPtr digest = ndn::crypto::sha256(hash_l->buf(), hash_l->size());
+  this->setHash(digest);
+}
+
+} // namespace nsl