Hi all, Paul, Mike, thank you for publishing the draft. I am happy to see ACME service discovery being discussed again.
For compare/contrast, I'd like to bring attention to my draft from a couple years ago, which proposed a DNS-SD profile for ACME service discovery, and which I presented at IETF 109: - https://www.ietf.org/archive/id/draft-tweedale-acme-discovery-01.html - https://datatracker.ietf.org/meeting/109/materials/slides-109-acme-service-discovery-00 Broadly contrasting the approaches, I note the following: - Use of CAA means that this mechanism is only useful for discovering ACME servers for DNS identifiers. There are ways you could work around this but they would use CAA records in improper ways. - The main problem solved in my draft was: "in this /network environment/, what ACME servers can/should I use?" The CAA-based proposal answers a different question: "for this /domain/, what ACME server should I use?" But (a) why would a domain owner need to control this, and (b) it doesn't actually solve the problem stated in the abstract: > This often leaves domain owners at the mercy of their hosting > provider as to which Certification Authorities (CAs) can be used. The hosting provider can still control which ACME servers can be reached, regardless of the preferences expressed via CAA records. Regarding registration of CAA attributes (IANA considerations): they need to be registered in the "Certification Authority Restriction Properties" registry: https://www.iana.org/assignments/pkix-parameters/pkix-parameters.xhtml#caa-properties Cheers, Fraser On Thu, Jul 06, 2023 at 06:33:01PM +0000, Paul van Brouwershaven wrote: > Hi Richard, > > Thanks for your feedback! > So if I understand this correctly, the idea is that an ACME client that > intends to obtain a certificate for > example.com<https://urldefense.com/v3/__http://example.com__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LXTPH7OoA$> > will look up CAA records for > example.com<https://urldefense.com/v3/__http://example.com__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LXTPH7OoA$> > and follow the guidance there as to which CA to contact? > Correct > Couple of observations on a quick skim: > > A brief "protocol overview" section might be helpful to capture the intended > happy-path flow. > Have you looked at the diagram in chapter 5, ACME Client Behavior? > https://www.ietf.org/archive/id/draft-vanbrouwershaven-acme-auto-discovery-01.html#name-acme-client-behavior > > Would you suggest renaming this chapter? > If folks are annoyed about the .well-known parts (as I am, a little): Since > you're going to extend CAA anyway, you could just put a URL in there instead > of overloading the CAA domain name. For example, instead of the `discover` > parameter being a boolean, you could just put the URL of the ACME server > directory there. (That would introduce a risk of divergence in the > multiple-domain case, different ACME servers for the same CA domain, but that > seems like it fails safely.) > We have indeed considered putting the ACME server directly in the CAA record, > as stated in paragraph 4 of chapter 4, ACME Client Configuration: > > While an alternative consideration was to include the ACME server address > directly as an attribute parameter in the CAA record, it was determined that > this approach could introduce clutter and significantly increase the size of > the record. Additionally, a rigid binding between the CAA record and the ACME > server address may present challenges if the CA needs to change its server > address in the future. > > https://www.ietf.org/archive/id/draft-vanbrouwershaven-acme-auto-discovery-01.html#name-acme-client-configuration > > In addition to the above, I would argue that the issuer domain name is much > easier for users to configure. > Section 3.1.2 says "the value "1" represents the highest priority", but > Section 3.2 includes "the highest priority of 0". In general, the document > should be clear on how the default interacts with explicit priorities. > Aaron Gable identified the same issue and created a pull request to address > and clarify the priorities. I just released a 01 version with these changes. > > ________________________________ > From: Richard Barnes <[email protected]> > Sent: Thursday, July 6, 2023 19:29 > To: Mike Ounsworth <[email protected]> > Cc: [email protected] <[email protected]>; Paul van Brouwershaven > <[email protected]> > Subject: Re: [Acme] FW: [EXTERNAL] New Version Notification for > draft-vanbrouwershaven-acme-auto-discovery-00.txt > > Hi Mike, Paul, > > So if I understand this correctly, the idea is that an ACME client that > intends to obtain a certificate for > example.com<https://urldefense.com/v3/__http://example.com__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LXTPH7OoA$> > will look up CAA records for > example.com<https://urldefense.com/v3/__http://example.com__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LXTPH7OoA$> > and follow the guidance there as to which CA to contact? > > Couple of observations on a quick skim: > > A brief "protocol overview" section might be helpful to capture the intended > happy-path flow. > > If folks are annoyed about the .well-known parts (as I am, a little): Since > you're going to extend CAA anyway, you could just put a URL in there instead > of overloading the CAA domain name. For example, instead of the `discover` > parameter being a boolean, you could just put the URL of the ACME server > directory there. (That would introduce a risk of divergence in the > multiple-domain case, different ACME servers for the same CA domain, but that > seems like it fails safely.) > > Section 3.1.2 says "the value "1" represents the highest priority", but > Section 3.2 includes "the highest priority of 0". In general, the document > should be clear on how the default interacts with explicit priorities. > > Cheers, > --RLB > > > > On Thu, Jul 6, 2023 at 10:55 AM Mike Ounsworth > <[email protected]<mailto:[email protected]>> > wrote: > Hi ACME! > > This is new business that we would like to add to the agenda for 117. > > Thanks, > --- > Mike Ounsworth & Paul van Brouwershaven > > -----Original Message----- > From: [email protected]<mailto:[email protected]> > <[email protected]<mailto:[email protected]>> > Sent: Thursday, July 6, 2023 9:39 AM > To: Mike Ounsworth > <[email protected]<mailto:[email protected]>>; Paul van > Brouwershaven > <[email protected]<mailto:[email protected]>> > Subject: [EXTERNAL] New Version Notification for > draft-vanbrouwershaven-acme-auto-discovery-00.txt > > WARNING: This email originated outside of Entrust. > DO NOT CLICK links or attachments unless you trust the sender and know the > content is safe. > > ______________________________________________________________________ > > A new version of I-D, draft-vanbrouwershaven-acme-auto-discovery-00.txt > has been successfully submitted by Paul van Brouwershaven and posted to the > IETF repository. > > Name: draft-vanbrouwershaven-acme-auto-discovery > Revision: 00 > Title: Auto-discovery mechanism for ACME client configuration > Document date: 2023-07-06 > Group: Individual Submission > Pages: 16 > URL: > https://www.ietf.org/archive/id/draft-vanbrouwershaven-acme-auto-discovery-00.txt<https://urldefense.com/v3/__https://www.ietf.org/archive/id/draft-vanbrouwershaven-acme-auto-discovery-00.txt__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LVAiwKnsg$> > Status: > https://datatracker.ietf.org/doc/draft-vanbrouwershaven-acme-auto-discovery/<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-vanbrouwershaven-acme-auto-discovery/__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LWMR1hgRw$> > Html: > https://www.ietf.org/archive/id/draft-vanbrouwershaven-acme-auto-discovery-00.html<https://urldefense.com/v3/__https://www.ietf.org/archive/id/draft-vanbrouwershaven-acme-auto-discovery-00.html__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LUJBCXjeQ$> > Htmlized: > https://datatracker.ietf.org/doc/html/draft-vanbrouwershaven-acme-auto-discovery<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/draft-vanbrouwershaven-acme-auto-discovery__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LWo1Szs0A$> > > > Abstract: > A significant impediment to the widespread adoption of the Automated > Certificate Management Environment (ACME) [RFC8555] is that ACME > clients need to be pre-configured with the URL of the ACME server to > be used. This often leaves domain owners at the mercy of their > hosting provider as to which Certification Authorities (CAs) can be > used. This specification provides a mechanism to bootstrap ACME > client configuration from a domain's DNS CAA Resource Record > [RFC8659], thus giving control of which CA(s) to use back to the > domain owner. > > Specifically, this document specifies two new extensions to the DNS > CAA Resource Record: the "discovery" and "priority" parameters. > Additionally, it registers the URI "/.well-known/acme" at which all > compliant ACME servers will host their ACME directory object. By > retrieving instructions for the ACME client from the authorized > CA(s), this mechanism allows for the domain owner to configure > multiple CAs in either load-balanced or fallback prioritizations > which improves user preferences and increases diversity in > certificate issuers. > > > > > The IETF Secretariat > > > Any email and files/attachments transmitted with it are intended solely for > the use of the individual or entity to whom they are addressed. If this > message has been sent to you in error, you must not copy, distribute or > disclose of the information it contains. Please notify Entrust immediately > and delete the message from your system. > _______________________________________________ > Acme mailing list > [email protected]<mailto:[email protected]> > https://www.ietf.org/mailman/listinfo/acme<https://urldefense.com/v3/__https://www.ietf.org/mailman/listinfo/acme__;!!FJ-Y8qCqXTj2!eD7c6YkKC17mdQGlDcEaGTQbmEgU6N2THkaQbM6RXa0FwMd1w2P8dNkfeej-TpOZBOANOymbB6sV_LWRYQnK_A$> > _______________________________________________ > Acme mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/acme _______________________________________________ Acme mailing list [email protected] https://www.ietf.org/mailman/listinfo/acme
