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Re: [TLS] Proposal to deprecate sha1 and md5 for digital signatures in TLS 1.2

Loganaden Velvindron <loganaden@gmail.com> Tue, 14 May 2019 18:16 UTC

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From: Loganaden Velvindron <loganaden@gmail.com>
Date: Tue, 14 May 2019 22:16:17 +0400
Message-ID: <CAOp4FwRRXYve8xjMhwHc9ihq-sQfjukjLvgToyWmf+yPsq0mDw@mail.gmail.com>
To: Hubert Kario <hkario@redhat.com>
Cc: "<tls@ietf.org>" <tls@ietf.org>, Martin Thomson <mt@lowentropy.net>
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Subject: Re: [TLS] Proposal to deprecate sha1 and md5 for digital signatures in TLS 1.2
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On Tue, May 14, 2019 at 3:24 PM Hubert Kario <hkario@redhat.com> wrote:

> On Tuesday, 14 May 2019 08:34:38 CEST Loganaden Velvindron wrote:
> > Latest draft is here:
> > https://www.ietf.org/id/draft-lvelvindron-tls-md5-sha1-deprecate-04.txt
>
> why did you drop SHA-1 from Section 4 and 5?
>
> It was done following this comment from David Cooper.
"
[..] While they may be subject to collision attacks, SHA-1 is still
considered secure in cases in which collision resistance is not required,
and I do not believe that collision resistance is required when SHA-1 is
used to create the "signatures" in the ServerKeyExchange and
CertificateVerify messages.
"



> the note about SHA-1 in HMAC applies to ciphersuites, to state explicitly
> that
> ciphersuites like TLS_DHE_RSA_WITH_AES_128_CBC_SHA are _not_ deprecated by
> it
>
> SKE and CV don't use HMAC
>
-- 
> Regards,
> Hubert Kario
> Senior Quality Engineer, QE BaseOS Security team
> Web: www.cz.redhat.com
> Red Hat Czech s.r.o., Purkyňova 115, 612 00  Brno, Czech Republic

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