I am trying to decrypt (and later encrypt) an email message (ebXML). The message contains a Signature element that contains child elements to specify the SignedInfo, SignatureValue and KeyInfo. Also, the message contains an encrypted attachment.

Question: What Java tools/apis should be used for decrypting? I would like to find some tool/api that would (automagically) instantiate objects based on whatever is included with the Signature element, so that the data (message) could be easily validated. And the other way around: Creating objects (specifying methods, signature value and keyinfo) and then outputting the xml to go into the message.