question: public void addSignatureTimestamp ( byte [ ] timestampDer ) throws Exception { Element unsignedProperties = getFirstElementByTagName ( document , xadesElement ( UNSIGNED_SIGNATURE_PROPS_TAG ) ) ; Element signatureTimeStampElement = document . createElement ( xadesElement ( SIGNATURE_TIMESTAMP_TAG ) ) ; String timestampDERBase64 = encodeBase64 ( timestampDer ) ; signatureTimeStampElement . setTextContent ( timestampDERBase64 ) ; unsignedProperties . insertBefore ( signatureTimeStampElement , unsignedProperties . getFirstChild ( ) ) ; }
target:  Adds the SignatureTimeStamp element containing the base64 encoded timestamp DER.