signature-info: add signed Interest elements

refs #4804

Change-Id: Ice910b7740212cf116ddac24e12634877f75c71e
diff --git a/tools/ndnsec/cert-gen.cpp b/tools/ndnsec/cert-gen.cpp
index 1749b2b..c526654 100644
--- a/tools/ndnsec/cert-gen.cpp
+++ b/tools/ndnsec/cert-gen.cpp
@@ -152,7 +152,7 @@
   SignatureInfo signatureInfo;
   signatureInfo.setValidityPeriod(security::ValidityPeriod(notBefore, notAfter));
   if (!additionalDescription.empty()) {
-    signatureInfo.appendTypeSpecificTlv(additionalDescription.wireEncode());
+    signatureInfo.addCustomTlv(additionalDescription.wireEncode());
   }
 
   security::Identity identity;