Re: [Acme] I-D Action: draft-ietf-acme-star-00.txt

[Martin Thomson <[e-mail]>]

One further thought. ACME uses an absolute time for expiration. This uses a
relative time. I think that I prefer the former. I realize that consistency
might be impossible in this case, since the recurrent duration is
necessarily relative, but I though it worth raising.

On 19 Jun. 2017 10:08 am, "Martin Thomson" <[e-mail]> wrote:

> A few brief comments on this draft.
>
> On 16 June 2017 at 22:19,  <[e-mail]> wrote:
> >    This memo proposes an ACME extension to enable the issuance of short-
> >    term and automatically renewed certificates.  This allows a domain
> >    name owner to delegate the use of certificates to another party,
> >    while retaining the capability to cancel this delegation at any time
> >    with no need to rely on certificate revocation mechanisms.
>
> I found the introduction overly specific.  The generic use case is to
> simplify the deployment of certificates to unprivileged nodes.  The
> unprivileged nodes then only need to be configured with a URL for
> their certificates.
>
> That requires a couple of paragraphs of exposition at most.  This
> extends to Section 2, which describes a system architecture that
> implies the existence of protocol elements that are simply not defined
> in this document.
>
> Sections 1 and 2 could much more clearly describe what *this* document
> provides.  It provides an extension to ACME that allows for the
> creation of a certificate that automatically renews.
>
> The focus on the CDN case affects the entire document.  The point is
> that the authorized entity is delegating the ability to use a
> certificate for its name to an unprivileged node.  Don't use "CDN",
> "content owner" or any of these highly specific terms.  Use generic
> terms; make new terms if necessary.  FWIW, while NDC is a cute
> reversal, "consumer" really isn't accurate.
>
> draft-iab-web-pki-problems has been abandoned.  It's not a great idea
> to cite it.
>
> In Section 3.1.1, I think that the resolution of these fields, being
> in days, is not conducive to reducing granularity.  (Or will you
> permit 5.7e-3 as a value?)
>
> Section 3.1.1 needs to clearly articulate how
> "recurrent-certificate-validity" (could this be any more verbose and
> hard to type?) relates to "expires".
>
> Please include a definition for the new attributes, rather than just
> providing an example and commenting the JSON.
>
> In Section 3.1.2, you REALLY, REALLY need to authenticate this
> request.  My suggestion is to change this to a POST request with {
> "recurrent": false }.  (I'd have suggested PUT or PATCH, but ACME's
> reliance on JWS perverts that in ways that is incompatible with those
> methods.)
>
> In Section 3.2, the discussion about a Proxy is misleading.  The only
> relevant actor in this is an ACME client.  This section could be
> reduced to:
>
> An ACME client discovers whether a server supports this extension by
> examining a newly created order.  The "recurrent" member will exist if
> the server supports automatic recurring certificate issuance; the
> "recurrent" member will be true if the server accepts the request.
>
> Can the server specify a shorter value for "recurrent-total-lifetime"?
>
> I don't understand Section 3.3 at all.  I'd recommend removing this
> section.  The DNO will decide what authorizations it requests amply
> without this level of proscription in standards.
>
> In Section 3.4, the use of the Expires header field is a common
> mistake.  This is an HTTP caching directive.  It should probably be
> shorter than the expiration time of the certificate (half in fact),
> but not for the reasons that you might think.  The purpose of a
> recommendation on Expires is to ensure that the certificate is not
> cached beyond the point where a newer certificate will be issued.  You
> should remove this text.
>
> Section 5.1 should be promoted to Section 5
>
> Don't mention time-sensitive policy actions by the CA/B Forum.
>
> Can't you simply ensure that the CDN can't modify the CAA record?
>