Adapt to ndn-cxx security changes

refs: #4090, #4195, #3828

Change-Id: Ie1bf11d604af12d3b26fba24054ed67fe735ae7c
diff --git a/src/state.hpp b/src/state.hpp
index 4fa82e9..8713552 100644
--- a/src/state.hpp
+++ b/src/state.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
 /*
- * Copyright (c) 2012-2014 University of California, Los Angeles
+ * Copyright (c) 2012-2017 University of California, Los Angeles
  *
  * This file is part of ChronoSync, synchronization library for distributed realtime
  * applications for NDN.
@@ -27,7 +27,7 @@
 
 #include "tlv.hpp"
 #include "leaf-container.hpp"
-#include <ndn-cxx/util/digest.hpp>
+#include <ndn-cxx/util/sha256.hpp>
 
 namespace chronosync {