Re: [Acme] Use of CAA in ACME

Richard Barnes <rlb@ipv.sx> Wed, 03 February 2016 20:42 UTC

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Date: Wed, 3 Feb 2016 15:42:55 -0500
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From: Richard Barnes <rlb@ipv.sx>
To: Phillip Hallam-Baker <phill@hallambaker.com>
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Subject: Re: [Acme] Use of CAA in ACME
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This seems like a fine idea.  You would need either a way to map from
domain names to ACME server URLs, or a new CAA record type to hold the
URL.  I would honestly kind of prefer the former, to avoid confusion.

I would also like to have a CAA record type for authorizing validation
methods, so that a domain holder can request that CAs only use certain
validation methods, regardless of what the ACME client requests.

Both of these ideas are good targets for a separate spec, since it's pretty
well decoupled from ACME itself.

On Wed, Feb 3, 2016 at 2:17 PM, Phillip Hallam-Baker <phill@hallambaker.com>
wrote:

> I would like to propose that we use RFC6844 to allow clients to
> discover the CA to direct requests to.
>
> A DNS name MAY have multiple CAA records. Each record has a tag
> specifying the purpose and a text field. So we would add in a text
> field for ACME.
>
> The simplest version would be something of the form:
>
> example.com CAA 0 acme "comodo.com"
>
>
> The typical enterprise case has the request going to an LRA because
> that is where the account key pair is held and that is what did the
> validation against the CA.
>
> I am thinking through that part.
>
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