Re: [dane] email canonicalization for SMIMEA owner names

Nico Williams <nico@cryptonector.com> Fri, 12 December 2014 04:16 UTC

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Date: Thu, 11 Dec 2014 22:16:46 -0600
From: Nico Williams <nico@cryptonector.com>
To: dane@ietf.org
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References: <95826148-4F06-4942-87A4-2F6601BA0F90@nist.gov> <20141211221456.GI3448@localhost> <20141211235519.GO25666@mournblade.imrryr.org> <20141212000953.B0FE5254EAE8@rock.dv.isc.org> <20141212003130.GQ25666@mournblade.imrryr.org> <20141212004131.09FDB254F4F4@rock.dv.isc.org> <20141212005550.GR25666@mournblade.imrryr.org> <20141212010007.2F78C254FBF3@rock.dv.isc.org> <CAF4kx8cXQYmfQ-3FVN64GFK_3mc0xt6ZYAXo9_NdFx0n1B+RXA@mail.gmail.com> <20141212013656.GT25666@mournblade.imrryr.org>
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Subject: Re: [dane] email canonicalization for SMIMEA owner names
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On Fri, Dec 12, 2014 at 01:36:56AM +0000, Viktor Dukhovni wrote:
> On Thu, Dec 11, 2014 at 05:22:03PM -0800, Ian Fette (????????) wrote:
> > Sorry, just reading the SMIMEA stuff for the first time, so apologies for
> > the basic question, but do I really have to publish a record for each
> > address? How would I say "this is a trusted intermediate CA for *@gmail.com
> > "?
> 
> That would look like so:
> 
>     ;; insert CNAMEs for any desired indirection when
>     ;; the same set of SMIMEA RRs handles multiple domains
>     ;;
>     *._smimecert.gmail.com IN SMIMEA 2 0 1 <blob>
> 
> Keep in mind that this only supports signature verification, not
> encryption, one can't encrypt to an intermediate CA, one needs the
> leaf public key for that.  So enabling encryption on first contact
> requires publishing per-user keys by some means.

There's always IBE, or just plain encrypting to the MTA's encryption
cert and then let it decrypt and re-encrypt to the local-part's
encryption key.

> Otherwise all one gets is authenticated key exchange, possibly
> followed later by encryption once leaf keys have been exchanged in
> both directions.

That's not so bad.  It's interactive, but so what.

Nico
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