[xmlsec] X509Data

Aleksey Sanin aleksey at aleksey.com
Tue Jul 18 15:54:16 PDT 2006

> "The entire certificate chain of the signer, including the root
> certificate, ...
Well, you can have root/trusted cert in the signed document but you
also MUST have it in the client in order to establish trust.

> X509Data elements. Each of the X509Data elements shall correspond to one
> certificate in the chain, and contain one X509IssuerSerial element and one
> X509Certificate element. The certificates may appear in any order."
> The research I've done seems to indicate that the entire certificate chain
> must be in one X509Data element.  Unfortunately I've not been able to get
> a definitive statement from the XML Digital Signature page that says that.
>  While researching this email, I just noticed the bit about the

 From XMLDsig spec

An X509Data element within KeyInfo contains one or more identifiers
of keys or X509 certificates....

My reading of this is that each X509Data element is a self contained
"pointer" to the key/certificate. Though, I can see arguments
against it.

> I have a couple of questions then.  Suppose I am unable to convince the
> author that his version is incorrect, and I have to work under those
> constraints.  How would you go about it?  I have a few ideas, but I would
> appreciate the advice.
Well, nothing is impossible, it's only software :) Probably the easiest
change to xmlsec would be to accumulate the content of all the X509Data
elements before actually processing them. Should not be too bad from
implementation point of view.

> Second, a more philosophical question I suppose.  How much of a fight
> should I put up on this?  Or am I completely mistaken in my assessment?

I would say that this significantly depends on the goals of your project 
and the behavior of other XMLDSig implementations (sorry, I never run
into this problem before). If all other toolkits are different from 
xmlsec then xmlsec needs to be fixed :) If you project does not care 
about interoperability  (though it might be a bad idea long term)
then this is one story. If you want to have interoperability and
all other XMLDsig toolkits do the same as xmlsec does then it is
another story.

BTW, please if you will be doing research of other xmldsig toolkits
behavior then I would really appreciate if you can post your results


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