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Re: [TLS] [FORGED] Re: no fallbacks please [was: Downgrade protection, fallbacks, and server time]

Peter Gutmann <pgut001@cs.auckland.ac.nz> Tue, 07 June 2016 06:00 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Dave Garrett <davemgarrett@gmail.com>, Hubert Kario <hkario@redhat.com>
Thread-Topic: [FORGED] Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]
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Date: Tue, 07 Jun 2016 06:00:33 +0000
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References: <CAF8qwaDuGyHOu_4kpWN+c+vJKXyERPJu-2xR+nu=sPzG5vZ+ag@mail.gmail.com> <201606031616.14451.davemgarrett@gmail.com> <1612869.mrh4f7qht5@pintsize.usersys.redhat.com>, <201606061453.53336.davemgarrett@gmail.com>
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Subject: Re: [TLS] [FORGED] Re: no fallbacks please [was: Downgrade protection, fallbacks, and server time]
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Dave Garrett <davemgarrett@gmail.com> writes:

>Also, as with any new system, we now have the ability to loudly stress to TLS
>1.3+ implementers to not screw it up and test for future-proofing this time
>around. 

I think that's the main contribution of a new mechanism, it doesn't really
matter whether it's communicated as a single value, a list, or interpretive
dance, the main thing is that there needs to be a single location where the
version is given (not multiple locations that can disagree with each other as
for TLS < 1.3), and the spec should include a pseudocode algorithm for dealing
with the version data rather than just "implementations should accept things
that look about right".

Peter.

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