security: Add SignatureSha256WithEcdsa

Change-Id: Ib3aa460d409c6d780b722e154ef2a620c510b16b
Refs: #1660
diff --git a/src/encoding/tlv.hpp b/src/encoding/tlv.hpp
index e56695c..9d70ee6 100644
--- a/src/encoding/tlv.hpp
+++ b/src/encoding/tlv.hpp
@@ -75,17 +75,21 @@
   AppPrivateBlock2 = 32767
 };
 
-enum SignatureType {
+enum SignatureTypeValue {
   DigestSha256 = 0,
-  SignatureSha256WithRsa = 1
+  SignatureSha256WithRsa = 1,
+  SignatureSha256WithEcdsa = 3
 };
 
-enum ConentType {
+enum ContentTypeValue {
   ContentType_Default = 0,
   ContentType_Link = 1,
   ContentType_Key = 2
 };
 
+/// @deprecated use ContentType instead
+typedef ContentTypeValue ConentType;
+
 /**
  * @brief Read VAR-NUMBER in NDN-TLV encoding
  *