Re: [TLS] A closer look at ROBOT, BB Attacks, timing attacks in general, and what we can do in TLS

Hubert Kario <hkario@redhat.com> Wed, 03 January 2018 11:51 UTC

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From: Hubert Kario <hkario@redhat.com>
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Date: Wed, 03 Jan 2018 12:51:53 +0100
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Subject: Re: [TLS] A closer look at ROBOT, BB Attacks, timing attacks in general, and what we can do in TLS
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On Friday, 15 December 2017 19:07:16 CET Eric Rescorla wrote:
> I'm not quite following how this helps. It's true that if SHA-256 is
> broken, we're in serious trouble, but that's largely because of the fact
> that that's what people's certificates have, so clients really can't refuse
> to support SHA-256 certificates. So, how does adding new algorithms help?
> (That's why I would argue that the existing SHA-384 support doesn't help).
> 

we are in the process of standardising Ed25519 for X.509 and TLS which doesn't 
use SHA-256 or SHA-384, so the fact that TLS will still use SHA-256 PRF with 
such certificates is a liability.

> On Fri, Dec 15, 2017 at 9:46 AM, Ilari Liusvaara <ilariliusvaara@welho.com>;
> 
> wrote:
> > On Fri, Dec 15, 2017 at 02:57:33PM +0000, Andrei Popov wrote:
> > > From: TLS [mailto:tls-bounces@ietf.org] On Behalf Of Ilari Liusvaara
> > > 
> > > > Even nastier dependency: SHA-2. If that breaks, currently both TLS
> > > > 1.2 and 1.3 break. There are no alternatives defined.
> > > 
> > > Here's an attempt to define a SHA-2 alternative:
> > https://tools.ietf.org/html/draft-wconner-blake2sigs-01
> > 
> > Also would need TLS ciphersuite codepoints with alternative handshake
> > hash algorithms.
> > 
> > 
> > -Ilari
> > 
> > _______________________________________________
> > TLS mailing list
> > TLS@ietf.org
> > https://www.ietf.org/mailman/listinfo/tls


-- 
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