Re: [TLS] Renumbering the new SignatureSchemes

Hubert Kario <hkario@redhat.com> Wed, 21 September 2016 10:21 UTC

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From: Hubert Kario <hkario@redhat.com>
To: David Benjamin <davidben@chromium.org>
Date: Wed, 21 Sep 2016 12:20:54 +0200
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Subject: Re: [TLS] Renumbering the new SignatureSchemes
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On Tuesday, 20 September 2016 18:24:42 CEST David Benjamin wrote:
> On Tue, Sep 20, 2016 at 2:14 PM Hubert Kario <hkario@redhat.com>; wrote:
> > I'll be running test looking for intolerances like this over the Alexa top
> > 1
> > million next month.
> 
> (I've already done this, by the way. It's where the numbers in the version
> negotiation thread came from.)

even if there is no glory in it, reproducibility studies are important in 
scientific approach :)

> > For now I have a probe that adds values 0x0003, 0x0004, 0x0700, 0x0703 and
> > 0x0704 at the end of the list of algorithms.
> 
> At the front is probably more realistic. 

good point

> There is even a MUST-level
> requirement in the current TLS 1.3 spec for SHA-1 sigalgs to be at the end,
> so the new ones can't be (unless you take SHA-1 out, which is, sadly,
> unrealistic today... an upsetting number of 1.2 servers only sign SHA-1).

yes, I see around 5% of servers doing that
 
> I was able to find a few instances of an NSS bug (
> https://bugzilla.mozilla.org/show_bug.cgi?id=1119983), but nothing else.
> 
> The offending implementation for this thread was actually a WebRTC stack
> (DTLS), not an HTTPS server. We hit it via Chrome's Dev channel. But since
> this intolerance comes from a MUST-level requirement in TLS 1.2, I think
> it's prudent to renumber.

True, but then we should check if we don't hit even bigger problems.

-- 
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