Thanks, I have no further comments and support merging this change.

Cheers,

Andrei

From: David Benjamin <david...@chromium.org>
Sent: Friday, June 21, 2024 12:03 PM
To: Andrei Popov <andrei.po...@microsoft.com>
Cc: Sean Turner <s...@sn3rd.com>; TLS List <tls@ietf.org>
Subject: Re: [TLS]Re: [EXTERNAL] Consensus Call: -rfc8446bis PR #1361

Thanks, Andrei! I have updated the PR to address your comments.

For some context, this came about because I noticed that the text in RFC 8446 
around the X.509 Key Usage extension was inconsistently applied to only the 
server certificate half and not the client certificate half. As checking 
consistency between X.509 Key Usage and the actual use is an important part of 
avoiding cross-protocol attacks, that seemed important to fix. For example, 
X.509 Key Usage is how you distinguish an ECDSA key from an ECDH key in X.509. 
It's even, bizarrely, how you distinguish an end-entity key from a CA key. One 
would think that's Basic Constraints, but Basic Constraints actually only 
allows you to say "this is not a CA key". It doesn't let you say "this is not 
an end-entity key". For that you use the fact that Key Usage uses distinct bits 
for "sign an X.509 payload" and "sign a protocol-specific payload". X.509 is 
truly amazing.

Anyway, poking from there revealed that, when we made the decision to unify the 
ClientHello -> Certificate and CertificateRequest -> Certificate extension flow 
in RFC 8446, we neglected to unify these two sections, so that PR fixes it.

On Fri, Jun 21, 2024 at 1:46 PM Andrei Popov 
<Andrei.Popov=40microsoft....@dmarc.ietf.org<mailto:40microsoft....@dmarc.ietf.org>>
 wrote:
Added a couple of minor comments; overall this change seems OK.

Cheers,

Andrei

-----Original Message-----
From: Sean Turner <s...@sn3rd.com<mailto:s...@sn3rd.com>>
Sent: Friday, June 21, 2024 10:15 AM
To: TLS List <tls@ietf.org<mailto:tls@ietf.org>>
Subject: [EXTERNAL] [TLS]Consensus Call: -rfc8446bis PR #1361

Hi! David Benjamin submitted the following PR to unify some prose related to 
certificate negotiation in TLS 1.3 (ClientHello/Certificate and 
CertificateRequest/Certificate are now nice and symmetric):
https://github.com/tlswg/tls13-spec/pull/1361
As this has been suggested post WGLC, we need to ensure we have consensus to 
merge this PR, so please review the PR in its entirety and indicate whether you 
support merging this PR by 5 July 23:59 UTC.

Cheers,
spt
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