Re: [Acme] Final thoughts on draft-ietf-acme-acme-05

Jacob Hoffman-Andrews <jsha@eff.org> Sun, 12 March 2017 19:11 UTC

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To: Hugo Landau <hlandau@devever.net>, acme@ietf.org
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From: Jacob Hoffman-Andrews <jsha@eff.org>
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Date: Sun, 12 Mar 2017 12:11:19 -0700
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Subject: Re: [Acme] Final thoughts on draft-ietf-acme-acme-05
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Thanks for the feedback, Hugo! And sorry I've taken so long to reply. I
think most of your comments have been addressed in merged or active PRs.

On 02/07/2017 09:15 PM, Hugo Landau wrote:
> Finally, I may as well mention wildcard domains again. I don't really
> get the aversion to standardizing this. I previously proposed that these
> be validated by n verification requests from a server to
> randomly-generated, unguessable labels substituting for a wildcard. This
> adequately proves that a wildcard is actually configured and that the
> service located by it is under account control. These would be blind;
> the hostnames used for the requests wouldn't be shown in the
> authorization or challenge objects, so the client wouldn't know what
> names would be used until the verification request comes in. Arguably,
> though, even this is overkill, and just creating authorization objects
> for unblinded, randomly generated names substituting for the wildcard
> would suffice. (In fact, as far as I can tell, nothing in the current
> spec actually prohibits doing this.)
>
> There are real applications for wildcard domains. For example, the
> ability to create unlimited numbers of secure origins has real value to
> some classes of web application.
Yep, I also think it would be nice to standardize wildcard issuance!
Richard's introduction of the "new-order" flow was intended to make
wildcard issuance at least possible, but there's still a big question
mark about what authorizations a server *should* create. To some extent
that is up to server policy, but I think it's worthwhile to recommend on
option.

Note that the CA/Browser Forum Ballot 169 validation rules indicated
that validating the base domain is sufficient to issue a wildcard
certificate, so we could just echo that. But my feeling of the group is
that folks would like to define a standard way of validating wildcards
that is better than that baseline.

Also: I think wildcards are a big enough topic that it probably doesn't
make sense to try and land any significant changes before the spec is
finalized, but they would be a good follow-on spec.