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

Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Tue, 12 May 2015 12:22 UTC

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Date: Tue, 12 May 2015 15:22:54 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Dave Garrett <davemgarrett@gmail.com>
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Subject: Re: [TLS] Update spec to match current practices for certificate chain order
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On Fri, May 08, 2015 at 07:35:13PM -0400, Dave Garrett wrote:
> A PR with language based on this discussion:
> https://github.com/tlswg/tls13-spec/pull/169/files
> 
> The text is mostly the same or similar, with the second "MUST" changed
> to a "SHOULD", and the term "trust anchor" replacing references to
> root keys/CA.
> 
> Is this changeset acceptable?

What's the point of this change? To allow server to send multiple
certificate chains (all starting from one EE cert) at once?

If it is that, why isn't topological ordering still required to
be correct (certificates signed preceed certificates signing)?

And does this proposed change allow server to send incomplete
certificate chains? According to SSL Pulse (May 2015), about
5% of servers have incomplete chains, and it is marked as a
problem.

Also, regarding "chain-building", one has to be careful with its
interaction with HPKP, which is currently as-deployed the _only_
mechanism that can be usefully used to harden a site against
misissued certificates (too bad it is qute a footgun, especially
due to chain rewriting).


-Ilari