Re: [kitten] draft-hansen-scram-sha256 and incorporating session hashing for channel binding

Nico Williams <nico@cryptonector.com> Sat, 23 May 2015 20:26 UTC

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Date: Sat, 23 May 2015 15:26:19 -0500
From: Nico Williams <nico@cryptonector.com>
To: Alexey Melnikov <alexey.melnikov@isode.com>
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References: <54DC00D0.2050900@cs.tcd.ie> <54EC66FF.50603@cs.tcd.ie> <54ECABD8.3090902@att.com> <87zj82f1yj.fsf@latte.josefsson.org> <54F4B8B8.8090406@isode.com>
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Subject: Re: [kitten] draft-hansen-scram-sha256 and incorporating session hashing for channel binding
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On Mon, Mar 02, 2015 at 07:23:36PM +0000, Alexey Melnikov wrote:
> On 25/02/2015 15:25, Simon Josefsson wrote:
> >Tony Hansen <tony@att.com> writes:
> >If people like the tls-session-hash approach (I'm not in that category,
> >but there may be consensus around it), the proper fix is to update RFC
> >5802 and reference tls-session-hash as a normative reference.  This will
> >take care of the problem, as you could copy that text into your
> >document.  If you are looking for a text change here, it would be:
> >
> >   To be secure SCRAM-SHA-256-PLUS has to be used over a TLS channel that
> >   MUST have [TLS-SESSION-HASH] negotiated.
> >
> >Personally, I would prefer to change to another mandatory channel
> >binding that is secure for all TLS versions.
> Before we make the decisions between referencing tls-session-hash
> versa a new channel binding, can you sketch out how the new channel
> binding is going to be defined?
> 
> (If we choose to define a new channel binding, I think Kitten WG is
> the right place for doing this work.)

There is no need to define a new channel binding.  Existing TLS
implementations need to be fixed regardless.  There's nothing GSS- or
SASL-mechanism-specific here.

Nico
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