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Re: [TLS] Deprecate SHA1 for signatures in TLS 1.3 (was Re: TLS 1.3 draft-07 sneak peek)

Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Tue, 07 July 2015 16:31 UTC

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Date: Tue, 07 Jul 2015 19:31:47 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Karthikeyan Bhargavan <karthik.bhargavan@gmail.com>
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Subject: Re: [TLS] Deprecate SHA1 for signatures in TLS 1.3 (was Re: TLS 1.3 draft-07 sneak peek)
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On Tue, Jul 07, 2015 at 12:16:04PM -0400, Karthikeyan Bhargavan wrote:
> > Let's distinguish between two different uses of SHA-1:
> > 
> > 1. In certificates.
> > 2. In TLS signatures.
> 
> I was recommending getting rid of (2).
> Getting rid of (1) would be nice, but I gather it relies on
> developments outside TLS.

Well, for "public" CA system, one can't get SHA-1 certs after
this year, neither Chrome nor Firefox accept those and Chrome
reacts rather badly to SHA-1 certs with expiration in 2017 or
later.

(Of course, this is just WebPKI, and there is plenty of other
stuff too).

And I don't think it is at all clear which of (1) or (2) is
actually worse for security (I think (1)).


-Ilari

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