diff --git a/core/leaf.hpp b/core/leaf.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_LEAF_HPP
+#define NLS_CORE_LEAF_HPP
+
+#include <vector>
+#include <ndn-cxx/util/crypto.hpp>
+#include "node.hpp"
+
+namespace nsl {
+
+class Leaf : public Node
+{
+public:
+
+  Leaf()
+    : Node()
+  {
+  }
+
+
+  Leaf(ndn::ConstBufferPtr data, uint64_t sequenceNumber, uint64_t level, time_t timestamp)
+    : Node(sequenceNumber, level, timestamp), m_data(data)
+  {
+  }
+
+
+  Leaf(const Leaf& new_leaf)
+    : Node(new_leaf.getIndex().number, new_leaf.getIndex().level, new_leaf.getTimestamp())
+  {
+    m_data = new_leaf.getData();
+    this->setHash(new_leaf.getHash());
+  }
+
+
+  ~Leaf()
+  {
+  }
+
+  ndn::ConstBufferPtr
+  getData() const;
+
+
+  void
+  computeHash();
+
+private:
+  ndn::ConstBufferPtr m_data;
+};
+
+} // namespace nsl
+
+#endif // NLS_CORE_LEAF_HPP