DER encoding: implement DerGtime::fromIsoString.
diff --git a/ndn-cpp/c/util/time.c b/ndn-cpp/c/util/time.c
index 41047f8..7ffa517 100644
--- a/ndn-cpp/c/util/time.c
+++ b/ndn-cpp/c/util/time.c
@@ -34,3 +34,23 @@
   sprintf(isoString, "%04d%02d%02dT%02d%02d%02d%s", 1900 + gmt->tm_year, gmt->tm_mon + 1, gmt->tm_mday,
     gmt->tm_hour, gmt->tm_min, gmt->tm_sec, fraction);
 }
+
+ndn_MillisecondsSince1970
+ndn_fromIsoString(const char* isoString)
+{
+  // Initialize time zone, etc.
+  time_t dummyTime = 0;
+  struct tm time = *gmtime(&dummyTime);
+  
+  sscanf(isoString, "%4d%2d%2dT%2d%2d", &time.tm_year, &time.tm_mon, &time.tm_mday, &time.tm_hour, &time.tm_min);
+  // Skip the time past minutes and get the float seconds.
+  double seconds;
+  sscanf(isoString + (4 + 2 + 2 + 1 + 2 + 2), "%lf", &seconds);
+  
+  // tm_year starts from 1900.
+  time.tm_year -= 1900;
+  // tm_mon starts from 0, not 1.
+  time.tm_mon -= 1;
+  time.tm_sec = 0;
+  return (timegm(&time) + seconds) * 1000.0;  
+}
\ No newline at end of file