diff --git a/src/encoding/cryptopp/asn_ext.cpp b/src/encoding/cryptopp/asn_ext.cpp
new file mode 100644
index 0000000..6698426
--- /dev/null
+++ b/src/encoding/cryptopp/asn_ext.cpp
@@ -0,0 +1,107 @@
+/**
+ * Copyright (C) 2013 Regents of the University of California.
+ * @author: Jeff Thompson <jefft0@remap.ucla.edu>
+ * @author: Yingdi Yu <yingdi@cs.ucla.edu>
+ * @author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ * See COPYING for copyright and distribution information.
+ */
+
+#include <ndn-cpp/ndn-cpp-config.h>
+#include "asn_ext.hpp"
+
+#if NDN_CPP_HAVE_TIME_H
+#include <time.h>
+#endif
+#if NDN_CPP_HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+
+#include <boost/format.hpp>
+#include <boost/lexical_cast.hpp>
+
+using namespace CryptoPP;
+
+namespace ndn {
+
+size_t
+DEREncodeGeneralTime(CryptoPP::BufferedTransformation &bt, MillisecondsSince1970 time)
+{
+#ifndef NDN_CPP_HAVE_GMTIME_SUPPORT
+  throw Asn::Error("Time functions are not supported by the standard library");
+#endif
+
+  if (time < 0)
+    throw Asn::Error("Calendar time value out of range");
+  else if (time > 2e14)
+    // 2e14 is about the year 8300.  We don't want to go over a 4-digit year.
+    throw Asn::Error("Calendar time value out of range");
+  
+  time_t secondsSince1970 = time / 1000;
+  struct tm* gmt = gmtime(&secondsSince1970);
+
+  std::string asn1time ((boost::format("%04d%02d%02d%02d%02d%02d%sZ")
+                         % (1900 + gmt->tm_year)
+                         % (gmt->tm_mon + 1)
+                         % gmt->tm_mday
+                         % gmt->tm_hour
+                         % gmt->tm_min
+                         % gmt->tm_sec).str());
+   // = os.str();
+  
+  bt.Put(GENERALIZED_TIME);
+  size_t lengthBytes = DERLengthEncode(bt, asn1time.size());
+  bt.Put(reinterpret_cast<const uint8_t*>(asn1time.c_str()), asn1time.size());
+  return 1+lengthBytes+asn1time.size();
+}
+
+void
+BERDecodeTime(CryptoPP::BufferedTransformation &bt, MillisecondsSince1970 &time)
+{
+  byte b;
+  if (!bt.Get(b) || (b != GENERALIZED_TIME && b != UTC_TIME))
+    BERDecodeError();
+
+  size_t bc;
+  if (!BERLengthDecode(bt, bc))
+    BERDecodeError();
+
+  SecByteBlock time_str(bc);
+  if (bc != bt.Get(time_str, bc))
+    BERDecodeError();
+
+  std::vector<std::string> params;
+  std::string current;
+  std::locale cLocale("C");
+  
+  for(uint32_t j = 0; j != time_str.size(); ++j)
+    {
+      if(std::isdigit(reinterpret_cast<char&>(time_str[j]), cLocale))
+        current += time_str[j];
+      else
+        {
+          if(current != "")
+            params.push_back(current);
+          current.clear();
+        }
+    }
+  if(current != "")
+    params.push_back(current);
+  
+  if(params.size() < 3 || params.size() > 6)
+    throw Asn::Error("Invalid time specification " + std::string(time_str.begin(), time_str.end()));
+
+  struct tm gmt;
+  gmt.tm_year = boost::lexical_cast<int>(params[0]);
+  gmt.tm_mon  = boost::lexical_cast<int>(params[1]) - 1;
+  gmt.tm_mday = boost::lexical_cast<int>(params[2]);
+  gmt.tm_hour = (params.size() >= 4) ? boost::lexical_cast<int>(params[3]) : 0;
+  gmt.tm_min  = (params.size() >= 5) ? boost::lexical_cast<int>(params[4]) : 0;
+  gmt.tm_sec  = (params.size() == 6) ? boost::lexical_cast<int>(params[5]) : 0;
+
+  if (b == GENERALIZED_TIME)
+    gmt.tm_year -= 1900;
+
+  time = timegm(&gmt) * 1000;
+}
+
+} // namespace ndn