**Breaking change** Use bzip2 compression of sync data payload

Change-Id: I0a322e3268a5adc9d221c23c43fc6899c9dbf836
Refs: #4140
diff --git a/src/bzip2-helper.hpp b/src/bzip2-helper.hpp
new file mode 100644
index 0000000..60485c4
--- /dev/null
+++ b/src/bzip2-helper.hpp
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2012-2018 University of California, Los Angeles
+ *
+ * This file is part of ChronoSync, synchronization library for distributed realtime
+ * applications for NDN.
+ *
+ * ChronoSync 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.
+ *
+ * ChronoSync 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
+ * ChronoSync, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef CHRONOSYNC_BZIP2_HELPER_HPP
+#define CHRONOSYNC_BZIP2_HELPER_HPP
+
+#include <ndn-cxx/encoding/buffer.hpp>
+
+namespace chronosync {
+namespace bzip2 {
+
+/**
+ * @brief Compress @p buffer of size @p bufferSize with bzip2
+ */
+std::shared_ptr<ndn::Buffer>
+compress(const char* buffer, size_t bufferSize);
+
+/**
+ * @brief Decompress buffer @p buffer of size @p bufferSize with bzip2
+ */
+std::shared_ptr<ndn::Buffer>
+decompress(const char* buffer, size_t bufferSize);
+
+} // namespace bzip2
+} // namespace chronosync
+
+#endif // CHRONOSYNC_BZIP2_HELPER_HPP