[ietf-dkim] Delegating responsibility: a make vs. buy design decision

[Scott Kitterman]

On Saturday 19 August 2006 18:49, Michael Thomas wrote:
> Scott Kitterman wrote:

> >Yes, but the fundamental operational problem will be to pick the correct
> >domain to sign with.
>
> If you know the submission authentication information, why is this hard?
> They authenticate as foo at bar.com, that means I pick the key for bar.com
> (and potentially foo if there's a g=). This doesn't seem like rocket
> science to me.
>
No, I don't think it's that hard either.  One earlier objection, that seemed 
to me to be the key concern for some was that in order to make third party 
signing safe it would be necessary to pick a different domain to sign with.  
My point here is that first party with NS delegation or with an authorization 
list it's the same issue.  

I think we agree on that point then.

> >You have to make thatd decision either way.  The basis
> >upon which you make the decision is the same.  I agree that the result
> > LOOKS less ambiguous with the NS delegation approach, but the fundamental
> > security issue is don't pick the wrong domain to sign with and that's no
> > different.
>
> No, the fundamental problem is that there's no way for a signer to relay
> that
> information to the receiver via i= when you're  a third party.
>
OK.  I didn't pick that up as the objection earlier (must be my density).  Let 
me think about that.  Off the top of my head, I don't see why it's a major 
issue, but I'll think about it.

Scott K