[Standards] [Fwd: I-D Action:draft-melnikov-digest-to-historic-00.txt]

Robin Redeker elmex at x-paste.de
Thu Sep 13 06:59:07 UTC 2007


On Wed, Sep 12, 2007 at 01:53:37PM +0100, Ian Paterson wrote:
> Peter Saint-Andre wrote:
> >Ian Paterson wrote:
> >  
> >>In real life servers will always be compromised (especially in cases
> >>where the attacker is the service provider). So SASL PLAIN still
> >>contains a serious vulnerability that is easily fixed in those cases
> >>where DIGEST-MD5 is a practical option.
> >>    
> >
> >Except that DIGEST-MD5 is effectively being deprecated by the IETF. Thus
> >the interest in SCRAM, YAP, and their ilk.
> >  
> 
> With all due respect to the experts at the IETF, I feel (as a 
> non-expert) that they are trying to depricate DIGEST-MD5 before it has a 
> suitable replacement (i.e. another one that protects users' passwords 
> from a compromised server). I strongly agree we should recommend/require 
> SCRAM and/or YAP as soon as they are baked. But is that likely to happen 
> before 3920bis is puiblished?
> 
> I agree that if we start recommending SASL PLAIN in addition to 
> DIGEST-MD5 now, *and if we continue to do so in the future*, then we can 
> ensure that current implementations will still be compatible with future 
> implementations that have removed support for DIGEST-MD5.
> 
> However I don't understand why we are considering recommending weakening 
> the security of XMPP servers in the short and medium term by not 
> requiring any of DIGEST-MD5 or SCRAM or YAP. Are XMPP implementors 
> experiencing interoperability issues with DIGEST-MD5?

One problem we encountered when talking about JID escaping and actually
trying it in the real world:

http://thread.gmane.org/gmane.network.jabber.standards-jig/16309/focus=16466

The most obvious solution would be: Clients and Servers that have broken
DIGEST-MD5 implementations should fix them ASAP.
Problem with that solution is: Even if the SASL implementations are
fixed fast (within few weeks) there will still be a lot of old servers
out there and old clients. That of course causes no direct interop
problems as noone uses \ in their JIDs yet.


Robin



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