Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]

Hubert Kario <hkario@redhat.com> Fri, 03 June 2016 13:29 UTC

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From: Hubert Kario <hkario@redhat.com>
To: tls@ietf.org
Date: Fri, 03 Jun 2016 15:28:59 +0200
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Subject: Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]
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On Friday 03 June 2016 07:39:06 Xiaoyin Liu wrote:
> > Date: Fri, 3 Jun 2016 11:33:54 +0300
> > From: ilariliusvaara@welho.com
> > To: tls@ietf.org
> > Subject: Re: [TLS] no fallbacks please [was: Downgrade protection,
> > fallbacks, and server time]> 
> > On Fri, Jun 03, 2016 at 08:37:34AM +0200, Nikos Mavrogiannopoulos 
wrote:
> > > A simpler proposal is:
> > > Consider TLS 1.3 as a feature, and negotiate it using an empty
> > > extension. If the extension is present a server assumes TLS 1.3.
> > 
> > Well, AFAIK, in current editor's draft, key_share or pre_shared_key
> > is always present and none are meaningful in TLS.1.2.
> 
> But they cannot be used to distinguish TLS 1.3 with any future
> versions, if these two extensions still exist in TLS 1.4, 1.5, ... .

TLSv1.4 and TLSv1.5 can introduce their own extensions, empty ones in 
worst case
-- 
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