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

Tony Hansen <tony@att.com> Tue, 24 February 2015 16:50 UTC

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Date: Tue, 24 Feb 2015 11:50:32 -0500
From: Tony Hansen <tony@att.com>
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Subject: [kitten] draft-hansen-scram-sha256 and incorporating session hashing for channel binding
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On 2/24/15 6:56 AM, Stephen Farrell wrote:
> But in addition, there were two substantive issues that ought be
> resolved before IETF LC:
>
> 1. a new channel binding or requiring tls-session-hash (and I guess
>     some explanatory text about why that is good/needed)

To recap:

Simon Josefsson made this comment:

> Since SCRAM was published, we have learned that the tls-unique channel
> binding is insecure -- it would be nice if we could combine the SHA256
> update with another default channel binding type to resolve that
> problem.  In my view, the problem with SCRAM today isn't primarily its
> use of SHA1 but it's broken channel binding.

Martin Thompson responded:

> We have a solution for that:
> https://tools.ietf.org/html/draft-ietf-tls-session-hash

I've read through tls-session-hash and am unsure how to proceed here.

One of my goals when proposing SCRAM-SHA-256 was to not change the 
protocol at all, other than updating the hash algorithm.

I'm not sure how to incorporate a recommendation for session hashing 
here. I'm thinking this would be best handled by adding something to the 
Security Considerations section. Does that seem right?

Would anyone be willing to suggest text changes for these comments?

     Tony Hansen