Re: [TLS] Comments on draft-rescorla-tls-renegotiate

Nicolas Williams <Nicolas.Williams@sun.com> Sat, 14 November 2009 08:42 UTC

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Date: Sat, 14 Nov 2009 02:31:36 -0600
From: Nicolas Williams <Nicolas.Williams@sun.com>
To: David-Sarah Hopwood <david-sarah@jacaranda.org>
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Cc: tls@ietf.org
Subject: Re: [TLS] Comments on draft-rescorla-tls-renegotiate
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On Sat, Nov 14, 2009 at 02:20:56AM +0000, David-Sarah Hopwood wrote:
> Nicolas Williams wrote:
> > Comments:
> > 
> > 1) The rest of this comment can be ignored if the use of protocol
> >    extensions in draft-rescorla-tls-renegotiate is deemed to not be a
> >    problem.
> > 
> >    [...]
> 
> The problem is that this unnecessarily breaks cases in which the
> possibility of attack couldn't have been prevented (because only
> one of the client and server supports the extension), and in which
> there may actually be no attack.

That's a feature: for how do you know that "there may actually be no
attack"??

Either we fix the vulnerability, or we don't.  The only middle of the
road is a "ask the user if this is OK" (client-side) or "allow but log"
(server-side) temporary transition configuration.

Nico
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