Re: [secdir] [xmpp] SecDir review of draft-ietf-xmpp-3920bis-17

Jeffrey Hutzelman <jhutz@cmu.edu> Wed, 03 November 2010 03:58 UTC

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Date: Tue, 02 Nov 2010 23:58:16 -0400
From: Jeffrey Hutzelman <jhutz@cmu.edu>
To: Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>, Peter Saint-Andre <stpeter@stpeter.im>
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Cc: draft-ietf-xmpp-3920bis.all@tools.ietf.org, The IESG <iesg@ietf.org>, XMPP Working Group <xmpp@ietf.org>, Security Area Directorate <secdir@ietf.org>
Subject: Re: [secdir] [xmpp] SecDir review of draft-ietf-xmpp-3920bis-17
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--On Tuesday, November 02, 2010 07:13:14 AM -0700 Kurt Zeilenga 
<Kurt.Zeilenga@Isode.COM>; wrote:

>
> On Nov 2, 2010, at 5:12 AM, Peter Saint-Andre wrote:
>
>> On 11/2/10 5:20 AM, Yaron Sheffer wrote:
>>> I'm OK with this text, including (sigh) PLAIN.
>>
>> If it's any consolation, I'm sighing along with you. :)
>>
>> Two points:
>>
>> 1. Eventually, we should be able to drop PLAIN in a future revision of
>> the MTI technologies spec that we'll pull out of 3920bis in 1+ years.
>
> Good luck with that.  The arguments used now for its inclusion is likely
> to be repeated and, again, win.
>
> Personally, I am against MUST'ing or SHOULD'ing TLS+PLAIN.  While it does
> offer good interoperability, it does good enough security for today's,
> and more importantly, tomorrow's Internet.
>
> I think we actually should be mandating a SCRAM-*-PLUS mechanism, because
> channeling bindings are really needed due to 'user click through' of TLS
> warnings, downgrade attack warnings, etc..   I do suspect that it will
> take time for this mechanism to be come ubiquitous, but I fear that
> without a MUST, it will never become ubiquitous.   But I do suspect well
> have multiple independently developed implementations of SCRAM-*-PLUS in
> XMPP within a few months of publication of this revision of XMPP.
>
> I suspect I'm in the rough on both points.  Oh well.
>
>> 2. The technology that the XMPP community uses for account registration
>> (XEP-0077) could benefit from an update, or even a replacement, and when
>> that work is completed I'd like to include a method by which a client
>> could register a key or cert with the server, thus smoothing the path
>> toward password-less authentication. IMHO that will be the best approach
>> in the longer term, instead of continually tweaking the password-based
>> methods. But that's a topic for another time...
>
> I also think transition-needed needs to be deprecated in favor of
> transition within the bound channel (e.g., today via XEP 77, tomorrow ?).

FWIW, I agree on all of these points.

-- Jeff