diff --git a/tools/ndnsec-op-tool.hpp b/tools/ndnsec-op-tool.hpp
new file mode 100644
index 0000000..a8d9421
--- /dev/null
+++ b/tools/ndnsec-op-tool.hpp
@@ -0,0 +1,96 @@
+/* -*- 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_OP_TOOL_HPP
+#define NDNSEC_OP_TOOL_HPP
+
+#include "ndnsec-util.hpp"
+
+using namespace std;
+
+int
+ndnsec_op_tool(int argc, char** argv)
+{
+  using namespace ndn;
+  namespace po = boost::program_options;
+
+  std::string command;
+  
+  po::options_description desc("General options");
+  desc.add_options()
+    ("help,h", "produce this help message")
+    ("command", po::value<std::string>(&command), "command")
+    ;
+
+  po::positional_options_description p;
+  p.add("command", 1);
+  
+  po::variables_map vm;
+  try
+    {
+      po::store(po::command_line_parser(argc, argv).options(desc).positional(p).run(), vm);
+      po::notify(vm);
+    }
+  catch(std::exception &e)
+    {
+      std::cerr << "ERROR: " << e.what() << std::endl;
+      return -1;
+    }
+    
+  if (vm.count("help"))
+    {
+      std::cerr << desc << std::endl;
+      return 0;
+    }
+  
+  if (0 == vm.count("command"))
+    {
+      std::cerr << "command must be specified" << std::endl;
+      std::cerr << desc << std::endl;
+      return 1;
+    }
+
+  if (command == "sign") // the content to be signed from stdin
+    {
+      try
+        {
+          KeyChain keyChain;
+
+          Buffer dataToSign((istreambuf_iterator<char>(cin)), istreambuf_iterator<char>());
+          
+          Signature signature = keyChain.sign(dataToSign.buf(), dataToSign.size(),
+                                              keyChain.getDefaultCertificateName());
+
+          if (signature.getValue().value_size() == 0)
+            {
+              std::cerr << "Error signing with default key" << std::endl;
+              return -1;
+            }
+
+          std::cout.write(reinterpret_cast<const char*>(signature.getValue().wire()), signature.getValue().size());
+        }
+      catch (boost::exception& e)
+        {
+          std::cerr << "ERROR: " << boost::diagnostic_information (e) << std::endl;
+          return -1;
+        }
+      catch (SecTpm::Error& e)
+        {
+          std::cerr << "ERROR: " << e.what() << std::endl;
+          return -1;
+        }
+      catch (SecPublicInfo::Error& e)
+        {
+          std::cerr << "ERROR: " << e.what() << std::endl;
+          return -1;
+        }
+    }
+
+  return 0;
+}
+
+#endif //NDNSEC_OP_TOOL_HPP