Subject: Re: WG Last Call: draft-ietf-krb-wg-tcp-expansion-00.txt

From: Simon Josefsson <[email-masked]>
Date: Fri, 07 Jul 2006 14:19:09 +0200

There were only one issue raised, but I'm not sure there were
consensus around it?

I won't be in Montreal; how do people feel about making the TLS I-D a
WG iten?  Maybe we can start discussions on that now, to have
something concrete to base the face-to-face discussions on.

If the status of the TLS draft isn't critical for moving the expansion
mechanism forward, I'd like to ask if there is anything else blocking
the expansion mechanism document now?

Thanks,
Simon

Jeffrey Hutzelman <[email-masked]> writes:

> This note announces the start of a two-week last call within the
> Kerberos Working Group on whether to send the following document to
> the IESG:
>
> Title:           Extended Kerberos Version 5 Key Distribtion Center
>                 (KDC) Exchanges over TCP
> Filename:        draft-ietf-krb-wg-tcp-expansion-00.txt
> Intended Status: Proposed Standard
>
>   This document describes an extensibility mechanism for the Kerberos
>   v5 protocol when used over TCP transports.
>
>
> This last call will expire at 23:59 EDT on June 22, 2006.
>
> Please review this document and send any comments to the Kerberos
> Working Group mailing list, <[email-masked]>, by that date.  The
> file can be obtained via
>
> http://www.ietf.org/internet-drafts/draft-ietf-krb-wg-tcp-expansion-00.txt
>
>
> -- Jeffrey T. Hutzelman (N3NHS) <[email-masked]>
>   Chair, IETF Kerberos Working Group
>   Carnegie Mellon University - Pittsburgh, PA

---

From: Sam Hartman <[email-masked]>
Date: Mon, 10 Jul 2006 09:13:44 -0400

>>>>> "Simon" == Simon Josefsson <[email-masked]> writes:

    Simon> There were only one issue raised, but I'm not sure there
    Simon> were consensus around it?

    Simon> I won't be in Montreal; how do people feel about making the
    Simon> TLS I-D a WG iten?  Maybe we can start discussions on that
    Simon> now, to have something concrete to base the face-to-face
    Simon> discussions on.

I think a TLS binding (or a DTLS binding) would be useful.  However I
think that you want to have some sort of channel binding/mixing of
keys.

    Simon> If the status of the TLS draft isn't critical for moving
    Simon> the expansion mechanism forward, I'd like to ask if there
    Simon> is anything else blocking the expansion mechanism document
    Simon> now?

As an individual, I don't think that the TLS document should be
blocking the extension mechanism.

---

From: Simon Josefsson <[email-masked]>
Date: Mon, 10 Jul 2006 15:32:32 +0200

> think that you want to have some sort of channel binding/mixing of

I see two choices -- a PA-DATA extension or a NULL-style encryption
suite with a channel binding field -- however, I'm not sure I
understand what attack would be prevented by having a channel binding
for Kerberos KDC exchanges.  Could you expand on that?  Presumably,
Kerberos without TLS is not vulnerable to the proxy-attack MITM, or at
least the vulnerabilities are acceptable (i.e., unprotected AS
exchanges are addressed by pre-auth?).  Why would there be more MITM
considerations when Kerberos is tunneled over TLS?

> blocking the extension mechanism.

FWIW, I agree.

/Simon

---

From: Simon Josefsson <[email-masked]>
Date: Fri, 28 Jul 2006 21:35:30 +0200

Perhaps my last e-mail was too verbose, I'll try again:

What is the outcome of the WGLC on this document?

Thanks,
Simon

---

From: Jeffrey Hutzelman <[email-masked]>
Date: Fri, 28 Jul 2006 15:51:44 -0400

> What is the outcome of the WGLC on this document?

If you read the agenda or summary or my slides for the Montreal meeting, 
you know that the WGLC on this document has ended.  It's waiting for me to 
finish my writeup.  In the process of doing that, I found some issues which 
will need to be resolved before this can move forward.  I'll explain those 
just as soon as a I get a chance; just at the moment, I'm a little swamped 
trying to fit a month's worth of work into two weeks between IETF and 
another trip next week.

-- Jeff

---

From: Simon Josefsson <[email-masked]>
Date: Fri, 28 Jul 2006 22:03:49 +0200

Jeffrey Hutzelman <[email-masked]> writes:

> If you read the agenda or summary or my slides for the Montreal
> meeting, you know that the WGLC on this document has ended.

Right.

> It's waiting for me to finish my writeup.

This was the piece of information that I was looking for.  Thanks.

> In the process of doing that, I found some issues which will need to
> be resolved before this can move forward.  I'll explain those just
> as soon as a I get a chance; just at the moment, I'm a little
> swamped trying to fit a month's worth of work into two weeks between
> IETF and another trip next week.

Understood!  No problem.

/Simon