Re: [TLS] WGLC for draft-ietf-tls-ticketrequests

Eric Rescorla <ekr@rtfm.com> Tue, 21 January 2020 15:17 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Tue, 21 Jan 2020 07:17:05 -0800
Message-ID: <CABcZeBMCWSmiRWQuQO60U0EGhpAcwisbWYFAqPUTZ5eb19Q3aQ@mail.gmail.com>
To: Martin Thomson <mt@lowentropy.net>
Cc: "<tls@ietf.org>" <tls@ietf.org>
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Subject: Re: [TLS] WGLC for draft-ietf-tls-ticketrequests
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I agree with Martin that this is unnecessary complexity.

In addition, I would note that switching to a new ticket *does* help even
if the server is using the same STEK because it improves privacy.

-Ekr


On Tue, Jan 21, 2020 at 12:58 AM Martin Thomson <mt@lowentropy.net>; wrote:

> On Tue, Jan 21, 2020, at 16:54, Viktor Dukhovni wrote:
> > There's no need to exclude valid use-cases.  The refined proposal
> > is rather non-invasive, and handles this case cost-effectively
> > on clients that re-use tickets (and don't use early-data, ...).
>
> I don't find your arguments persuasive.  This adds complexity specifically
> to address a case that has - in the general case - suboptimal
> characteristics, both in terms of forward secrecy and linkability.  Whether
> or not there are specific cases that might tolerate these suboptimalities,
> the complexity and risks are borne by everyone.
>
> This is clearly a subjective call, so I'll step back now.
>
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