Re: <ds:Signature/> and <Signature/>

> 
> When Java tries to process the C signature it expects the URI to be there.
> If not it will throw an exception.

You might want to file a bug report against apache. The URI attribute is
optional according to the spec:

http://www.w3.org/TR/xmldsig-core/#sec-Reference

Best,
Aleksey Sanin