diff --git a/ndn-cpp/key-chain.cpp b/ndn-cpp/key-chain.cpp
index c2a10ff..1da6f9d 100644
--- a/ndn-cpp/key-chain.cpp
+++ b/ndn-cpp/key-chain.cpp
@@ -106,7 +106,7 @@
   if ((error = ndn_encodeBinaryXmlData(&dataStruct, &signedFieldsBeginOffset, &signedFieldsEndOffset, &encoder)))
     throw std::runtime_error(ndn_getErrorString(error));
   
-  digestSha256(encoder.output.array + signedFieldsBeginOffset, signedFieldsEndOffset - signedFieldsBeginOffset, digest);
+  digestSha256(&encoder.getOutput()->front() + signedFieldsBeginOffset, signedFieldsEndOffset - signedFieldsBeginOffset, digest);
 }
 
 void KeyChain::sign