diff --git a/tools/ndnsec-set-default.hpp b/tools/ndnsec-set-default.hpp
new file mode 100644
index 0000000..86c831a
--- /dev/null
+++ b/tools/ndnsec-set-default.hpp
@@ -0,0 +1,93 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2013, Regents of the University of California
+ * BSD license, See the LICENSE file for more information
+ * Author: Yingdi Yu <yingdi@cs.ucla.edu>
+ */
+
+#ifndef NDNSEC_SET_DEFAULT_HPP
+#define NDNSEC_SET_DEFAULT_HPP
+
+int 
+ndnsec_set_default(int argc, char** argv)	
+{
+  using namespace ndn;
+  namespace po = boost::program_options;
+
+  std::string certFileName;
+  bool setDefaultId = true;
+  bool setDefaultKey = false;
+  bool setDefaultCert = false;
+  std::string name;
+
+  po::options_description desc("General Usage\n  ndnsec set-default [-h] [-K|C] name\nGeneral options");
+  desc.add_options()
+    ("help,h", "produce help message")
+    ("default_key,K", "set default key of the identity")
+    ("default_cert,C", "set default certificate of the key")
+    ("name,n", po::value<std::string>(&name), "the name to set")
+    ;
+
+  po::positional_options_description p;
+  p.add("name", 1);
+  po::variables_map vm;
+  po::store(po::command_line_parser(argc, argv).options(desc).positional(p).run(), vm);
+
+  po::notify(vm);
+
+  if (vm.count("help")) 
+    {
+      std::cerr << desc << std::endl;
+      return 0;
+    }
+
+  try
+    {
+      KeyChain keyChain;
+
+      if (vm.count("default_key"))
+        {
+          setDefaultKey = true;
+          setDefaultId = false;
+        }
+      else if(vm.count("default_cert"))
+        {
+          setDefaultCert = true;
+          setDefaultId = false;
+        }
+
+      if (setDefaultId)
+        {
+          Name idName(name);
+          keyChain.setDefaultIdentity(idName);
+          return 0;
+        }
+      if (setDefaultKey)
+        {
+          Name keyName(name);
+          keyChain.setDefaultKeyNameForIdentity(keyName);
+          return 0;
+        }
+
+      if (setDefaultCert)
+        {
+          keyChain.setDefaultCertificateNameForKey(name);
+          return 0;
+        }
+
+      return 1;
+
+    }
+  catch(SecPublicInfo::Error& e)
+    {
+      std::cerr << e.what() << std::endl;
+      return 1;
+    }
+  catch(SecTpm::Error& e)
+    {
+      std::cerr << e.what() << std::endl;
+      return 1;
+    }
+
+}
+#endif //NDNSEC_SET_DEFAULT_HPP