Re: [kitten] last call: draft-ietf-kitten-tls-channel-bindings-for-tls13-02

Hi Sam, Kittens,

Summary: Yeah, ready, I think, but a tiny bit of wordsmithing might benefit.

Main Issue:

Use with TLS 1.2 is not entirely clear. I think all the information is
there, but it's a little scattered, and I misread the "When TLS
renegotiation is enabled (pre TLS 1.3)" initially. While TLS 1.3 is
obviously desirable, there's enough TLS 1.2 out there that making this
clear would be a benefit.

So I would personally extract the last paragraph of §2 and the first from
§3 into a new section (§2.1, §3.1, or something else). A suggestion of
actual text for this new version (mostly a cut and paste). I'm not sure if
the "must" wants to be a MUST here, either:

Use with earlier TLS versions

   While it is possible to use this channel binding mechanism with TLS
   versions below 1.3, extra precaution must be taken to ensure that the
   chosen cipher suites always result in unique master secrets.  For
   more information see the Security Considerations section of
   [RFC5705].

   In addition, session renegotiation MUST NOT be enabled. When TLS
   renegotiation is enabled the "tls-exporter" channel binding type is not
   defined and implementations MUST NOT support it.

If you use this suggestion, you may wish to include a "Other security
considerations are discussed throughout this document" in Security
Considerations, and you may wish to do that anyway.

You may also want to drive home the point that people really ought to just
use 1.3.

Many thanks for writing this document and riding it through, I fully intend
to implement as and when the APIs surface.

Dave.

On Wed, 10 Mar 2021 at 19:26, Robbie Harwood <rharwood@redhat.com> wrote:

> Hello kitten and TLS,
>
> Our document defining TLS 1.3 channel bindings is now in 2-week last
> call (to end 2021-03-24).  That document can be viewed at:
>
>
> https://datatracker.ietf.org/doc/draft-ietf-kitten-tls-channel-bindings-for-tls13/
>
> If you read the document during this period, please submit a review in
> reply (even if it's just that you think it's ready), especially if you
> are more active in TLS than kitten.  This helps me judge consensus.
>
> Thanks,
> --Robbie
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