diff --git a/model/hash-helper.h b/model/hash-helper.h
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+/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2011 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: Ilya Moiseenko <iliamo@cs.ucla.edu>
+ */
+
+#ifndef ccnx_hash_helper_h
+#define ccnx_hash_helper_h
+
+#include <string>
+#include <boost/unordered_map.hpp>
+#include <boost/functional/hash.hpp>
+#include <boost/foreach.hpp>
+
+//size of content store
+#define NDN_CONTENT_STORE_SIZE 100
+//maximum length of content name
+#define NDN_MAX_NAME_LENGTH 30
+
+//using namespace std;
+
+#define KEY(x)		x->first
+#define VALUE(x)	x->second
+
+
+/*template<typename T> 
+struct hash : public std::unary_function<T, std::size_t> {
+    std::size_t operator()(T const&) const;
+};*/
+
+struct string_hash : public std::unary_function<std::string, std::size_t>
+{
+	inline std::size_t operator( )( std::string str ) const
+	{
+        std::size_t hash = str.size() + 23;
+		for( std::string::const_iterator it = str.begin( ); it!=str.end(); it++ )
+		{
+			hash = ((hash << 6) ^ (hash >> 27)) + static_cast<std::size_t>( *it );
+		}
+		
+		return boost::hash_value(hash); //hash;
+	}
+};
+
+// A collision-chaining hash table mapping strings to ints.
+template<typename Value>
+class string_key_hash_t : public boost::unordered_map<std::string,Value, string_hash, std::equal_to<std::string>,std::allocator<std::string> >
+{
+};
+
+#endif
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