Re: [TLS] Collisions (Re: Nico's suggestions - Re: Consensus Call:

Nicolas Williams <Nicolas.Williams@oracle.com> Tue, 11 May 2010 20:07 UTC

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Date: Tue, 11 May 2010 15:07:28 -0500
From: Nicolas Williams <Nicolas.Williams@oracle.com>
To: Marsh Ray <marsh@extendedsubset.com>
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Cc: "Kemp, David P." <DPKemp@missi.ncsc.mil>, tls@ietf.org
Subject: Re: [TLS] Collisions (Re: Nico's suggestions - Re: Consensus Call:
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On Tue, May 11, 2010 at 03:04:38PM -0500, Marsh Ray wrote:
> On 5/11/2010 2:46 PM, Nicolas Williams wrote:
> > On Tue, May 11, 2010 at 02:32:12PM -0500, Marsh Ray wrote:
> >> So how much better is this caching scheme than what you could have today
> >> with session resumption?
> > 
> > I recall this question being asked long ago.  IIRC the idea is that you
> > could cache a cert chain for many servers' certs
> 
> Isn't one of the implications of the choice of a non-collision-resistant
> hash that you must use a completely separate cache for each hostname?

I don't think that's clear yet.  However, it is clear that making this
extension safe will require more care than it seemed to me the first
time I glanced at it.  It may well be that the answer to your question
is "yes", in which case I think you'd be right that session resumption
is plenty good enough.