RIF: How much XML Signature is mature?

Thank you for your answer, Blake.   

>What types of document artifacts do you need to authenticate?

whatever ... as usual, the business gives not clear & changeable requirements :) ... or better still, it's very dangerous taking them as final ...

>XML Signature is great for situations where XML data must be selectively
>signed based on XML document
>subsets. The situation that you have described doesn't immediately point
>to a multi-hop signing environment with
>multiple intermediate signers.

in effect, this is not a requirement and I'm a strong believer in minimal implementations. Actually, evaluating XML Signature makes sense here if there are strong advantages in implementing all 'plumbing' related to sign/verify a general XML element ... something like: sign this element given my profile  ... verify this element, given sender's profile. Then, since this is an implementation of a standard, features such as the ones you mentioned could be eventually simpler to support in the future ... By contrast, there are (also) the disadvantages you mentioned. 

Gino