diff --git a/core/sub-tree-binary.hpp b/core/sub-tree-binary.hpp
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+++ b/core/sub-tree-binary.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/>.
+ *
+ * See AUTHORS.md for complete list of nsl authors and contributors.
+ */
+
+#ifndef NSL_CORE_SUB_TREE_HPP
+#define NSL_CORE_SUB_TREE_HPP
+
+#include "node.hpp"
+
+namespace nsl {
+
+typedef std::function<void(const Node::Index&)> CompleteCallback;
+typedef std::function<void(const Node::Index&,
+                           const NonNegativeInteger&,
+                           ndn::ConstBufferPtr)> RootUpdateCallback;
+
+class SubTreeBinary
+{
+public:
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : std::runtime_error(what)
+    {
+    }
+  };
+
+public:
+  /**
+   * @brief Constructor
+   *
+   * Create an empty subtree.
+   *
+   * @param loggerName The name of logger
+   * @param completeCallback Callback when the subtree is complete
+   * @param rootUpdateCallback Callback when the subtree root is updated
+   */
+  SubTreeBinary(const Name& loggerName,
+                const CompleteCallback& completeCallback,
+                const RootUpdateCallback& rootUpdateCallback);
+  /**
+   * @brief Constructor
+   *
+   * Create a subtree with its first leaf node hash.
+   *
+   * @param loggerName The name of logger
+   * @param rootIndex The index of sub tree root when it is full
+   * @param completeCallback Callback when the subtree is complete
+   * @param rootUpdateCallback Callback when the subtree root is updated
+   */
+  SubTreeBinary(const Name& loggerName,
+                const Node::Index& rootIndex,
+                const CompleteCallback& completeCallback,
+                const RootUpdateCallback& rootUpdateCallback);
+
+  const Node::Index&
+  getPeakIndex() const
+  {
+    return m_peakIndex;
+  }
+
+  const NonNegativeInteger&
+  getMinSeqNo() const
+  {
+    return m_minSeqNo;
+  }
+
+  const NonNegativeInteger&
+  getMaxSeqNo() const
+  {
+    return m_maxSeqNo;
+  }
+
+  size_t
+  getLeafLevel() const
+  {
+    return m_leafLevel;
+  }
+
+  const NonNegativeInteger&
+  getNextLeafSeqNo() const;
+
+  /**
+   * @brief get the root of the subtree
+   *
+   * @return pointer to the root, nullptr if no leaf added
+   */
+  ConstNodePtr
+  getRoot() const
+  {
+    return m_actualRoot;
+  }
+
+  ndn::ConstBufferPtr
+  getRootHash() const;
+
+  ConstNodePtr
+  getNode(const Node::Index& index) const;
+
+  bool
+  addLeaf(NodePtr leaf);
+
+  bool
+  updateLeaf(const NonNegativeInteger& nextSeqNo, ndn::ConstBufferPtr hash);
+
+  bool
+  isFull() const;
+
+  shared_ptr<Data>
+  encode() const;
+
+  void
+  decode(const Data& data);
+
+public:
+  static Node::Index
+  toSubTreePeakIndex(const Node::Index& index, bool notRoot = true);
+
+private:
+  void
+  initialize(const Node::Index& peakIndex);
+
+  void
+  updateActualRoot(NodePtr node);
+
+  void
+  updateParentNode(NodePtr node);
+
+public:
+  static const size_t SUB_TREE_DEPTH;
+
+NSL_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
+  static const time::milliseconds INCOMPLETE_FRESHNESS_PERIOD;
+  static const std::string COMPONENT_COMPLETE;
+  static const ssize_t OFFSET_ROOTHASH;
+  static const ssize_t OFFSET_COMPLETE;
+  static const ssize_t OFFSET_SEQNO;
+  static const ssize_t OFFSET_LEVEL;
+  static const size_t N_LOGGER_SUFFIX;
+
+private:
+  Name m_loggerName;
+  Node::Index m_peakIndex;
+  NonNegativeInteger m_minSeqNo;
+  NonNegativeInteger m_maxSeqNo;
+  size_t m_leafLevel;
+
+  CompleteCallback m_completeCallback;
+  RootUpdateCallback m_rootUpdateCallback;
+
+  NodePtr m_actualRoot;
+  bool m_isPendingLeafEmpty;
+  NonNegativeInteger m_pendingLeafSeqNo;
+
+  std::map<Node::Index, NodePtr> m_nodes;
+};
+
+typedef shared_ptr<SubTreeBinary> SubTreeBinaryPtr;
+typedef shared_ptr<const SubTreeBinary> ConstSubTreeBinaryPtr;
+
+} // namespace nsl
+
+#endif // NSL_CORE_SUB_TREE_HPP