Implement encoding/decoding SignedInfo content Type.
diff --git a/ndn-cpp/c/errors.h b/ndn-cpp/c/errors.h
index 2e64492..da8548f 100644
--- a/ndn-cpp/c/errors.h
+++ b/ndn-cpp/c/errors.h
@@ -32,6 +32,7 @@
   NDN_ERROR_DynamicUCharArray_realloc_function_pointer_not_supplied,
   NDN_ERROR_DynamicUCharArray_realloc_failed,
   NDN_ERROR_unrecognized_ndn_ExcludeType,
+  NDN_ERROR_unrecognized_ndn_ContentType,
   NDN_ERROR_unrecognized_ndn_KeyLocatorType,
   NDN_ERROR_unrecognized_ndn_KeyNameType,
   NDN_ERROR_decodeBinaryXmlKeyLocator_unrecognized_key_locator_type,