Another question (Signatures)

Hey all,

Another obvious thought (I'm good at them :>).

I assume there is a requirement on implementations to ensure that the 
signature(s) in a message actually refer(s) to the XKMS content.  That's 
probably pretty obvious, but I can see some fairly trivial attacks 
against implementations that just check a signature is valid without 
ensuring that the reference actualy refers to the XKMS message.

Is this something worth mentioning in the security section?

Cheers,
	Berin