Re: [TLS] MD5 diediedie (was Re: Deprecating TLS 1.0, 1.1 and SHA1 signature algorithms)

Hubert Kario <hkario@redhat.com> Tue, 12 January 2016 13:32 UTC

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From: Hubert Kario <hkario@redhat.com>
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Date: Tue, 12 Jan 2016 14:10:23 +0100
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Subject: Re: [TLS] MD5 diediedie (was Re: Deprecating TLS 1.0, 1.1 and SHA1 signature algorithms)
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On Tuesday 12 January 2016 05:32:08 Viktor Dukhovni wrote:
> On Mon, Jan 11, 2016 at 10:42:45PM -0500, Dave Garrett wrote:
> > No sane person disputes that MD5 needs to be eradicated ASAP. We're
> > keeping MD5||SHA1 in old TLS for compatibility and we are well
> > aware that needs to go eventually too. Thus, I suggest we publish
> > an MD5 diediedie standards track RFC to prohibit ALL standalone MD5
> > use in ALL IETF
> > protocols/standards.
> 
> With some exceptions, for example:
> 
>     * As you note in your last comment, X.509 self-signatures via
>     MD5 may continue to be ignored, once MD5 is "banned" in the same
>     way that they should have been ignored before it was "banned".
> 
>     * S/MIME parsers may continue to parse old S/MIME messages with
>       MD/5 signatures.  More generally, Encrypted data at rest may
>       need support for MD5 for the lifetime of the data (until
>       re-encrypted, ...).

in case of digital signatures, that means "lifetime of the data", you 
can't expect them being possible to re-sign

so it must not completely forbid use of MD-5 in implementations of stuff 
like PAdES-A. Though it should strongly recommend allowing its use in 
only *very* specific circumstances.

-- 
Regards,
Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purky┼łova 99/71, 612 45, Brno, Czech Republic