Re: retrieving the digest value from an enveloped signature

["Jozef Aerts - Comp.Chem.Cons. - XML4Pharma" <co...@hotmail.com>]

I need this in a demo application about signing and verifying clinical data 
form, in order to show the standardizing organization (CDISC in this case) 
how they can use XML-Signature in their own standard as the signing 
mechanism.

What I want to show is that if one character in the original XML changes, 
one gets a totally different digest value, thus leading to an invalid 
signature.

I could already resolve the first issue (retrieving the published digest 
value from the Signature element), but could not find out how to 
re-calculate the digest value of the original document (is it possible 
anyway with the Apache implementation?)

Best regards

Jozef Aerts
Computer Chemistry Consultancy - XML4Pharma


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