Re: [TLS] Update spec to match current practices for certificate chain order

mrex@sap.com (Martin Rex) Thu, 07 May 2015 14:32 UTC

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To: Peter Gutmann <pgut001@cs.auckland.ac.nz>
Date: Thu, 7 May 2015 16:32:07 +0200 (CEST)
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From: mrex@sap.com (Martin Rex)
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Subject: Re: [TLS] Update spec to match current practices for certificate chain order
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Peter Gutmann wrote:
> Martin Rex <mrex@sap.com> writes:
> >Peter Gutmann wrote:
> >> For example my code looks for a cert containing the site name
> >> ("www.whatever.com") and then builds a chain up via the parent links until it
> >> can't find any more useful certs.  That just works no matter what the other
> >> side sends.
> >
> >Adding workarounds for clearly bogus behaviour is a very bad strategy,
> >because it makes the situation worse for everyone in the long run.
> 
> In my case (and possibly others) it's not a workaround since the same code
> that does PKCS #7/CMS also does TLS cert chains, in order to handle the more
> open-ended PKCS #7 requirements it automatically deals with oddball TLS
> chains.

PKCS#7/CMS uses a Issuer&Serial (or alternatively SKI) to clearly
identify the end-entity certificate.  In TLS, the identification is
the first position in certificate_list.  So it is not possible
to "blindly reuse" the code with respect to identifying the
end-entity certificate.

For the certificate path beyond the end entity certificate, the approach
may be similar.

-Martin