[Servercert-wg] EV Certificates through automation / Pre-Authorized Certificate Approver (API)

Paul van Brouwershaven Paul.vanBrouwershaven at entrust.com
Fri Feb 2 15:01:31 UTC 2024

An ACME key and API key are both credentials but just in a different from, I provided the examples with API keys as these are most widely used today.

We do indeed use the External Account Binding (EAB), and this works for a setup where the user can configure the ACME server at the Cloud Service Provider (ACME client) and provide the EAB to the Cloud Service Provider, unfortunately this is rarely the case, as I presented at F2F#59 in Redmond<https://cabforum.org/wp-content/uploads/F2F-59-CABF-SCWG-ACME-Automation.pdf>.

This is why we have been working on an auto discovery mechanism for ACME<https://datatracker.ietf.org/doc/draft-vanbrouwershaven-acme-auto-discovery/>, and this works fine for domain validated certificates as you do not need an EAB for that, but we would also like to ensure that identity certificates can be supported by this proposal.

A domain and organization can be pre-linked at the CA, after verification of domain control and the organization identity.

With ACME its simple to validate domain control for each request, this could be precondition when there is no explicit and unique account binding. But proving domain control does not equal an authorization of a Certificate Approver as required for the issuance of an EV certificate.

Like linking an ACME client key via an External Account Binding (EAB) to a Pre-Authorized Certificate Approver, according to 11.8.4 of the EVG, to support EV certificates over ACME. We could link the ACME keys of an Cloud Service Provider at the CA side without EAB if these would be disclosed for linking (like via a manual or by publishing them to the well-known directory).

My initial thought is that this would give the same guarantee as when the user provides an EAB to the Cloud Service Provider which links that to an ACME client key that is shared between all customers as we are just reversing the process.

> Do we need the concept of Certificate Approver?
The idea that a human approves individual certificates requests doesn't align with the desire for automation.

The concept of a Pre-Authorized certificate approver (EVG 11.8.4) seems to be trying to address this issue by allowing multiple future EV Certificate Requests.

With API keys linked to Pre-Authorized certificate approvers, we assume that all requests made with this API key are on behalf of that Pre-Authorized certificate approver, where in reality they are made by a system, which could be a third party.

I think we want to have approval by the organization that certificates which include the organization in the subject DN can be issued for a given domain name/FQDN, but this is something that can be pre-approved for each domain name/FQDN and doesn't have to be specified per certificate request.

From: Doug Beattie
Sent: Friday, February 02, 2024 12:48
To: Paul van Brouwershaven; CA/B Forum Server Certificate WG Public Discussion List
Subject: [EXTERNAL] RE: EV Certificates through automation / Pre-Authorized Certificate Approver (API)

Hi Paul,

Thanks for that presentation.

I’m assuming that Entrust uses External Account Binding (EAB) to link the MAC key and KeyID to the customer account.  Are these the API credentials you’re referring to in the presentation?

Another way to look into automating for EV is asking the question: Do we need the concept of Certificate Approver?  While there was probably value in this back when the EVGs were created, is there continued value of this in 2024, especially in light of the need to automate?



From: Servercert-wg <servercert-wg-bounces at cabforum.org> On Behalf Of Paul van Brouwershaven via Servercert-wg
Sent: Thursday, February 1, 2024 12:41 PM
To: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org>
Subject: [Servercert-wg] EV Certificates through automation / Pre-Authorized Certificate Approver (API)

As briefly introduced on the Server Certificate WG Teleconference, I would like to bring up a topic around the use of API keys that are linked to a Pre-Authorized Certificate Approver.

Please find some reference slides attached.

Slide 3:
How I think API keys with a Pre-Authorized Certificate Approver are implemented today.

Slide 4:
If the API key fulfills the same requirements and is authorized by the Certificate Approver, does it matter who creates/holds the API key with authorization of the Certificate Approver?

Slide 5:
Does this change if the authorization was given based on a reference to an API key, like located in a well-known directory of the Cloud Service Provider (CSP)? The idea is that this could enable ACME auto discovery<https://datatracker.ietf.org/doc/draft-vanbrouwershaven-acme-auto-discovery/> for OV and EV certificates as the Certificate Approver explicitly approves the CSP to request certificates on their behalf.

It would be great to get people’s thoughts on this!


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