Re: [ietf-dkim] Re: I-D ACTION:draft-ietf-dkim-overview-04.txt

Eliot Lear wrote:
> Hi,
> > Given two sets of RECEIVERS:
> >
> >   RECEIVER-A:  Legacy DKIM-BASE system. Supports DKIM-BASE only
> >   RECEIVER-B:  Updated to support DKIM-BASE+SSP
> >
> > and given a DOMAIN that has determined that it "better" to use SSP 
> > than not use SSP, therefore it uses a strong SSP policy for signing.
> > then who do you think the BAD GUY will target?
> >
> >   Simple:  RECEIVER-A
> >
> > RECEIVER-A will bare the blunt of the premature decisions.  The DOMAIN 
> > reputation will be harmed because there exist a legacy of DKIM-BASE 
> > only systems that bad guys will target.
> First, I'm not sure how DOMAIN comes into this equation.  I suspect that 
> RECEIVER-A will maintain a list of domains, either manually or out of 
> band, that it knows signs messages, and may then weight messages from 
> those domains with invalid signatures somewhat toward spam.  The only 
> issue is that RECEIVER-A may not be able to make an easy decision about 
> a message with an invalid signature from a domain that has no SSP 
> record.  Perhaps it doesn't sign any mail.
Right, or the DOMAIN signs all mail and Bad Guys (BG) target legacy 
systems, including RECEIVER-A DKIM-BASE only systems with no signature 
mail purportedly from this DOMAIN   BGs will stay away from RECEIVER-B 
type systems.
> > So using the word "break" is not a term I would use.  But I would say 
> > that the promotion and recommendation that it is SAFE to use DKIM-BASE 
> > without any helper technology is in my strong opinion, a very poor 
> > engineering decision because it HARM receivers and domains.
> I just don't see this.
Fair enough, it is just a consequence of the above which is not much 
different than today with BGs targetting legacy systems.  Receiver-A, 
including non-DKIM ready system will feel the blunt of the exploitation. 
    The unsuspecting domains, who unbeknowst to them, their domain is 
being used in vain at these sites (spoofed, phished), are harmed.   No 
different than it is today.   I'm just hoping that we don't begin march 
into a new era with the same mistakes of opening new holes due to 
incomplete considerations.
> > Of course, RECEIVER-A would have to upgrade and I believe that is 
> > question Mr. Lear was poising to Mr. Powers.  Will systems upgrade at 
> > a later point?
> No, my question was directed at Dave Crocker and Tony Hansen about 
> whether they would be willing to revise the overview document.
My apology. Rereading your message, I misread it to mean you were asking 
 Mr Powers if they would upgrade (software) since he showed an urgency 
to get an operation going now.  My bad, I read you wrong. Sorry.
--
HLS


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