Re: Poll: use of TLS channel bindings in SCRAM

[Nicolas Williams <Nicolas.Williams@xxxxxxx>]

On Fri, May 29, 2009 at 06:56:04PM -0700, Kurt Zeilenga wrote:
> 
> On May 29, 2009, at 5:22 PM, Nicolas Williams wrote:
> >I believe that making GS2 support in-mechanism negotiation of channel
> >binding type now or in the future would require _significant_  
> >surgery on
> >GS2.
> 
> So your proposal does preclude one possible negotiation approach that  
> could be used in SCRAM and GS2.

I never claimed that there were no schemes that were not precluded.
We've shown that three future channel binding negotiation schemes, one
of them your personal favorite, are not precluded by our proposal.  We
can't and should not seek to make all possible schemes remain feasible
-- I shouldn't have to point out how silly it would be to try.

Also, to be perfectly fair: I misspoke.  It is not the case that our
proposal precludes GS2/SCRAM having in-mechanism CB type negotiation!
It's GS2's design itself.

> >It's too late to be doing major changes to GS2.  Moreover, where
> 
> >is the justification for requiring that GS2 support such a thing?  If
> >you believe that GS2 should support that, then please explain why, and
> >then let's have a poll on that.
> 
> 
> You asserted:
>   Notice too that we are left in a position where we can actually add  
> channel binding type negotiation later.

And that was and remains true.  Why are you trying to play gotcha?  What
purpose does it serve?

> My assertion is that while certainly we might be able to to add  
> channel binding type negotiation, the particulars of the SCRAM and GS2  
> specifications will have a significant impact on the engineering of  
> solutions.   Hence, I believe it appropriate to discuss the impact  
> upon possible solutions during the consideration of the particulars of  
> the SCRAM and GS2 specification.

Nonsense.