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

Dave Garrett <davemgarrett@gmail.com> Tue, 07 July 2015 16:42 UTC

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From: Dave Garrett <davemgarrett@gmail.com>
To: Eric Rescorla <ekr@rtfm.com>
Date: Tue, 07 Jul 2015 12:42:22 -0400
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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 Tuesday, July 07, 2015 12:08:30 pm Eric Rescorla wrote:
> Let's distinguish between two different uses of SHA-1:
> 
> 1. In certificates.
> 2. In TLS signatures.
> 
> I have no problem with insisting that TLS 1.3 not do SHA-1 for signatures in
> the protocol. However, given that there are lots of SHA-1 certificates in the
> field and the world is bigger than browsers, it seems like forbidding use of
> SHA-1 in certificates for TLS 1.3 (while it's still available to TLS 1.2) acts
> mostly as a disincentive to adoption for TLS 1.3, so I'm currently not in
> favor of that.

On Tuesday, July 07, 2015 12:10:15 pm Eric Rescorla wrote:
> On Tue, Jul 7, 2015 at 8:35 AM, Dave Garrett <davemgarrett@gmail.com> wrote:
> > PR:
> > https://github.com/tlswg/tls13-spec/pull/188/files
> > Issue:
> > https://github.com/tlswg/tls13-spec/issues/186
> 
> This PR seems to prohibit use of SHA-1 for certificates as well, which I'm
> not sure is wise. I suggest we put this on the agenda for Prague.

How does it prohibit SHA1 in certs? The commit message might be unclear, but it only modifies the signature algorithms extension.


Dave

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