DER encoding: implement DerGtime::fromIsoString.
diff --git a/ndn-cpp/c/util/time.h b/ndn-cpp/c/util/time.h
index 454216e..b2414c7 100644
--- a/ndn-cpp/c/util/time.h
+++ b/ndn-cpp/c/util/time.h
@@ -21,13 +21,21 @@
 ndn_getNowMilliseconds();
 
 /**
- * Convert the time from milliseconds to ISO time, for example "20131018T184138.423355".
+ * Convert the time from milliseconds to an ISO time string, for example "20131018T184138.423355".
  * @param milliseconds The time in milliseconds since 1/1/1970, including fractions of a millisecond.
  * @param isoString A buffer of at least 23 bytes to receive the null-terminated ISO time string.
  */
 void
 ndn_toIsoString(ndn_MillisecondsSince1970 time, char *isoString);
 
+/**
+ * Parse the ISO time string and return the time in milliseconds.
+ * @param isoString The ISO time string, for example "20131018T184138.423355".
+ * @return The time in milliseconds since 1/1/1970, including fractions of a millisecond.
+ */
+ndn_MillisecondsSince1970
+ndn_fromIsoString(const char* isoString);
+
 #ifdef  __cplusplus
 }
 #endif