throws ReferenceNotInitializedException, XMLSignatureException {
OutputStream os = null;
try {
MessageDigestAlgorithm mda = this.getMessageDigestAlgorithm();
mda.reset();
DigesterOutputStream diOs = new DigesterOutputStream(mda);
os = new UnsyncBufferedOutputStream(diOs);
XMLSignatureInput output = this.dereferenceURIandPerformTransforms(os);
// if signing and c14n11 property == true explicitly add
// C14N11 transform if needed