diff --git a/core/merkle-tree.hpp b/core/merkle-tree.hpp
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+++ b/core/merkle-tree.hpp
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+/* -*- 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>
+ */
+#ifndef NLS_CORE_MERKLE_TREE_HPP
+#define NLS_CORE_MERKLE_TREE_HPP
+
+#include <map>
+#include <vector>
+
+#include <stddef.h>
+#include <stdint.h>
+#include <time.h>
+
+#include "leaf.hpp"
+#include "intermediate-node.hpp"
+#include "merkle-tree-cache.hpp"
+
+namespace nsl {
+
+class MerkleTree
+{
+public:
+  MerkleTree();
+
+  ~MerkleTree()
+  {
+  }
+
+  ConstNodePtr
+  getNode(const Index& index);
+
+  uint64_t
+  getLeafNum() const;
+
+  uint64_t
+  getLevel() const;
+
+
+  //return root hash value
+  uint64_t
+  addLeaf(ndn::ConstBufferPtr info);
+
+
+  std::vector<ConstNodePtr>
+  generateProof(uint64_t version1, uint64_t version2); // version equals to leaf's index number
+
+
+private:
+  MerkleTreeCache m_cache;
+  uint64_t m_nLevels;
+  uint64_t m_nLeaves;
+
+};
+
+
+} // namespace nsl
+
+#endif // NLS_CORE_MERKLE_TREE_HPP