diff --git a/nsync/src/sync-seq-no.cc b/nsync/src/sync-seq-no.cc
new file mode 100644
index 0000000..fbbc53f
--- /dev/null
+++ b/nsync/src/sync-seq-no.cc
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2012 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Zhenkai Zhu <zhenkai@cs.ucla.edu>
+ *         Chaoyi Bian <bcy@pku.edu.cn>
+ *	   Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#include "sync-seq-no.h"
+#include <boost/make_shared.hpp>
+
+using namespace boost;
+
+namespace Sync {
+
+DigestConstPtr
+SeqNo::getDigest () const
+{
+  DigestPtr digest = make_shared<Digest> ();
+  *digest << m_session << m_seq;
+  digest->finalize ();
+  return digest;
+}
+
+} // Sync