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Re: [Cfrg] Help with the use of contexts

Adam Langley <agl@imperialviolet.org> Tue, 17 January 2017 16:12 UTC

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From: Adam Langley <agl@imperialviolet.org>
Date: Tue, 17 Jan 2017 08:12:16 -0800
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To: Yaron Sheffer <yaronf.ietf@gmail.com>
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Subject: Re: [Cfrg] Help with the use of contexts
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On Tue, Jan 17, 2017 at 3:31 AM, Yaron Sheffer <yaronf.ietf@gmail.com> wrote:
> Wide industry adoption of TLS 1.2 took around 10 years. So IMO saying "this
> is solved in TLS 1.3" is not a good enough answer, if in the meantime we
> will continue to see cross-protocol and cross-TLS-version attacks.

If there are such attacks then they'll continue to be a problem for
TLS 1.2 because only the Ed* schemes have the possibility of a context
string. For ECDSA and RSA, the context still needs to be included in
the signed message somehow. So TLS 1.2 needs a larger change than
wiring up the context inputs of the Ed* schemes if you want to protect
it anyway.


Cheers

AGL

-- 
Adam Langley agl@imperialviolet.org https://www.imperialviolet.org

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