Re: [dane] email canonicalization for SMIMEA owner names

Nico Williams <> Fri, 12 December 2014 16:21 UTC

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Date: Fri, 12 Dec 2014 10:21:09 -0600
From: Nico Williams <>
To: Paul Wouters <>
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Subject: Re: [dane] email canonicalization for SMIMEA owner names
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On Fri, Dec 12, 2014 at 11:12:56AM -0500, Paul Wouters wrote:
> On Thu, 11 Dec 2014, Nico Williams wrote:
> >Yes: use MSA/MTA as the keyserver, both for lookup and registration.
> Why add another service, another dependancy and another choke point and
> another trans protocol for auditing that the world sees the same view?

Well, it's another service on a protocol that already exists, that the
MUA must speak, and has similar functionality (VRFY) anyways.

> That can all be done with DNS.

If done *only* with DNS then we get into the canonicalization/zone
walking (spam) trap and we then have to do something that sucks.

> Adding another service just adds more problems.

So does not adding it.  It's a case of pick your poison.

I can't say I like one poison better than the other yet...

BTW, for the DNS-only scheme, there's no need for local-part canon when
verifying sender certs: because hopefully! the sender's MUA will use a canonical
sender local-part.

As for looking up a recipient's encryption cert...  well, if the MUA
gets the wrong recipient local-part form as a result of applying an
incorrect canonicalization, then it could get the wrong recipient -- a
relatively minor problem, but one worth noting.

The SMIMEA I-D does need to describe the motions that the MUA goes
through to do the two different tasks: verifying sender signature certs,
and finding recipient encryption certs.