Re: [dane] Review of DANE SMTP draft

Viktor Dukhovni <viktor1dane@dukhovni.org> Mon, 17 March 2014 23:06 UTC

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Date: Mon, 17 Mar 2014 23:06:46 +0000
From: Viktor Dukhovni <viktor1dane@dukhovni.org>
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Subject: Re: [dane] Review of DANE SMTP draft
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On Mon, Mar 17, 2014 at 11:34:07PM +0100, Martin Rex wrote:

>    2.  If the wildcard character is the only character of the left-most
>        label in the presented identifier, the client SHOULD NOT compare
>        against anything but the left-most label of the reference
>        identifier (e.g., *.example.com would match foo.example.com but
>        not bar.foo.example.com or example.com).

I am aware of this SHOULD NOT.  The question is whether this is
the right behaviour for opportunistic DANE TLS.  There is no user
to "click OK", and if Postini-style wildcard certs are likely to
be employed or need to be employed, then perhaps the right choice
for SMTP is to tolerate multi-label wildcards.

I am not insisting one way or the other, just wondering whether
there is consensus.  Fortunately, there is a UTA draft on name
checks for SMTP, and its authors have invited me to pitch in.

Their draft defines wildcards to match a single label, and this
question is perhaps best dealt with on the UTA list (where I may
again run into Martin and the rest of our fine DANE crew, but it
seems to be a more natural forum for what is I think more of an
application question).

So most likely SMTP name checks will not specifically endorse
multi-label wildcards, but if it is OK with this group, I'd like
to move this specific issue to that forum.

-- 
	Viktor.