Subject: Re: [Ietf-krb-wg] tls and channel binding

From: Nicolas Williams <[email-masked]>
Date: Mon, 10 Dec 2007 15:00:55 -0600

On Wed, Nov 28, 2007 at 12:51:38PM -0600, Nicolas Williams wrote:
> On Wed, Nov 28, 2007 at 10:39:11AM -0800, Henry B. Hotz wrote:
> > How does this affect SSPI compatibility?
> 
> You must mean: can this be implemented using SSPI, or <pick your
> favorite TLS API>?
> 
> The short answer is: not my problem.  If some TLS API lacks a way to
> obtain the channel binding of a TLS connection, then pick another API/
> implementation or file an RFE with the implementor.
> 
> This may sound harsh, but keep in mind that: a) FAST + PKINIT is the
> primary solution in this space (i.e., we have consensus for that), while

Actually, we don't have consensus on which should be the required-to-
implement solution, FAST + PKINIT or StartTLS.

I much prefer to use off-the-shelf solutions.  Before PKINIT StartTLS
would have been the off-the-shelf solution to use.  Now we have two,
with PKINIT being the slightly more appropriate solution, IMO.  Ideally
we shouldn't have invented PKINIT, and instead had StartTLS with channel
binding all along.  But we didn't.

Now we have a situation in which some implementors prefer one
off-the-shelf solution while others prefer the other.  Oops.

I don't envy the WG chairs the task of helping the WG converge on one
solution or the other.

That said, I think *both* proposals need to provide for channel binding
of PA-ENC-TIMESTAMP and future PAs that can possibly do channel binding.

(No, we don't have a rule that says that channel binding must be part of
a spec where it makes sense.  But I think we're probably headed that
way, and anyways, we should do it where it's simple, as it is in the
case of StartTLS.)

Nico
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From: Leif Johansson <[email-masked]>
Date: Mon, 10 Dec 2007 22:47:22 +0100

Nicolas Williams wrote:

<snip>
> binding all along.  But we didn't.
FWIW I agree completely with this.

    Cheers Leif

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From: Nicolas Williams <[email-masked]>
Date: Mon, 10 Dec 2007 16:30:54 -0600

> FWIW I agree completely with this.

We all might agree with that and, sadly, still be no closer to
consensus.
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From: Leif Johansson <[email-masked]>
Date: Tue, 11 Dec 2007 12:41:17 +0100

> We all might agree with that and, sadly, still be no closer to
I think we have rough consensus. I just think it needs to be asserted.

    Cheers Leif