Re: [TLS] Finished stuffing/PSK Binders

Martin Thomson <martin.thomson@gmail.com> Wed, 12 October 2016 10:43 UTC

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From: Martin Thomson <martin.thomson@gmail.com>
Date: Wed, 12 Oct 2016 21:43:05 +1100
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To: Ilari Liusvaara <ilariliusvaara@welho.com>
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Subject: Re: [TLS] Finished stuffing/PSK Binders
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On 12 October 2016 at 19:50, Ilari Liusvaara <ilariliusvaara@welho.com>; wrote:
> I also noticed another edge case: What is to prevent server from
> omitting key share group (emitting a cookie, so the restart is
> not spurious), presumably causing the client to blank its key_share
> and then proceed to accept DH versus client's previously sent share?

How about: If key_share isn't in the HRR, the client should replay
it's old key_share verbatim.  Though I agree that the text should say
as much.

Maybe we should require text for every extension that can appear in
the HRR: what to do if the extension is in the HRR, and what to do if
it isn't.