Re: [TLS] Version negotiation, take two

Hubert Kario <hkario@redhat.com> Thu, 15 September 2016 18:03 UTC

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From: Hubert Kario <hkario@redhat.com>
To: tls@ietf.org
Date: Thu, 15 Sep 2016 20:03:03 +0200
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Subject: Re: [TLS] Version negotiation, take two
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On Thursday, 15 September 2016 11:51:31 CEST Benjamin Kaduk wrote:
> On 09/14/2016 02:02 PM, Andrei Popov wrote:
> > Basically, I don't feel strongly about the switch to the proposed version
> > negotiation mechanism. But if we are going to make this change based on
> > the theory of having only one extension point and actively defending it,
> > then we should probably follow the theory and send a separate TLS
> > extension per TLS version.
> To me, the (ordered) list of client supported versions in a single
> extension feels more intuitively natural, so I want to try harder to
> understand the reasoning that leads you to prefer a separate extension
> for each version.  Is it just that doing an additional "negotiation"
> within the extension body constitutes another extension point that we
> would have to actively defend, or is there something else about what a
> TLS extension is philosophically supposed to indicate?

the extensions joint is well greased and works

the lists inside extensions are a hit and miss, they mostly work, but then we 
have SNI in general, signature methods in past NSS versions, and if you dug 
more I wouldn't be surprised if you found half a dozen other issues just like 
it (in late October I may have actual numbers about it)

-- 
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