I have an XML document which is already Xades signed. Now I want to counter sign this signature. How can I do this with Xades4j? I have searched the documentation but there is only example how to sign and countersign together.Answer1:
You can use a <a href="http://code.google.com/p/xades4j/wiki/SignatureEnrichment#Creating_an_Extender" rel="nofollow">format extender</a> directly to <a href="http://xades4j.googlecode.com/svn/release/1.3.0/javadoc/reference/xades4j/production/XadesSignatureFormatExtender.html" rel="nofollow">add new unsigned properties</a> to an existing signature.