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

Peter Gutmann <> Tue, 07 June 2016 06:00 UTC

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From: Peter Gutmann <>
To: Dave Garrett <>, Hubert Kario <>
Thread-Topic: [FORGED] Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]
Date: Tue, 7 Jun 2016 06:00:33 +0000
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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 <>; 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

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".