Re: [TLS] [Last-Call] Last Call: <draft-ietf-tls-oldversions-deprecate-09.txt> (Deprecating TLSv1.0 and TLSv1.1) to Best Current Practice

Stephen Farrell <stephen.farrell@cs.tcd.ie> Tue, 01 December 2020 00:50 UTC

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To: Peter Gutmann <pgut001@cs.auckland.ac.nz>, Keith Moore <moore@network-heretics.com>, "last-call@ietf.org" <last-call@ietf.org>
Cc: "draft-ietf-tls-oldversions-deprecate@ietf.org" <draft-ietf-tls-oldversions-deprecate@ietf.org>, "tls-chairs@ietf.org" <tls-chairs@ietf.org>, "tls@ietf.org" <tls@ietf.org>
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From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Date: Tue, 1 Dec 2020 00:48:29 +0000
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Subject: Re: [TLS] [Last-Call] Last Call: <draft-ietf-tls-oldversions-deprecate-09.txt> (Deprecating TLSv1.0 and TLSv1.1) to Best Current Practice
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Hiya,

On 01/12/2020 00:29, Peter Gutmann wrote:
> However I think your comment points out the overall problem:
> 
>    usage in web, mail and OSes
> 
> This means there's no consideration at all of use in embedded/SCADA/whatever.

I wouldn't agree with "no consideration" but guess we might
agree about a lack of data. In particular, mail servers
within enterprises were an explicit consideration but one
where the consensus I think ended up pretty clear to be to
deprecate despite at that time ongoing non-trivial usage of
old versions.

That said, if someone had words to suggest that might garner
consensus, that would be good. I earlier said I'd try craft
such, and will, but maybe better to start that with text from
someone who works with these deliberately update-averse
devices. (My guess as of now, is that would need to try
describe cases where our "MUST NOT" is really an rfc6919
"MUST NOT (but we know you will)" rather than an attempt to
characterise all the situations where the "MUST NOT" is
clearly correct.)

Cheers,
S.

PS: I think the earlier discussion referred to above answers
Keith's point about mail servers, if one looks back over it.
(That's from memory though, me not actually having gone back
and looked over it again... yet;-)