[Servercert-wg] MPIC implementation & protocol / API standardization

Tue Sep 3 08:12:04 UTC 2024

Dear fellow CA reps,

Together with the vendor of our PKI system, we're now at the point where we either use their code to run as remote perspectives (either on VMs hosted in any of the public cloud providers or VMs running in our datacenters with outbound VPNs that terminate at suitable remote locations) or standardize the protocol / API between the primary (local) perspective and the remotes and then use any other (i.e. open source) implementation of the remote perspective.

We are aware of the Open MPIC initiative which is very valuable. At the moment, they seem to focus on providing a "complete" MPIC solution and their API specification implements a single call to perform the corroboration from multiple perspectives all at once. Also, Open MPIC's choice of AWS Lambda functions for the implementation is – while totally elegant – not in line with our strategy for programming language and cloud usage.

We're currently more focusing on a protocol / API that specifies the call to one remote perspective and an implementation that can be run in a VM/Docker container.

After my last mail, two interested CAs contacted me privately and showed interest in collaboration on the implementation of MPIC. Are there any other CAs working on this and willing to share / collaborate?

Kind regards
Roman

From: Roman Fischer
Sent: Mittwoch, 22. Mai 2024 09:29
To: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org>
Subject: RE: [Servercert-wg] Discussion Period Begins - Ballot SC-067 V3: "Require domain validation and CAA checks to be performed from multiple Network Perspectives"

Dear colleagues,

We have started internal discussions about possible architectures to implement this new feature. This of course also involves the vendor of our CA system because architecture of the remote perspectives has big impacts on the changes needed in the CA system.

One of the ideas we were brainstorming involves partnering with other CAs to share remote perspectives. Of course this would require some standardized protocol, mutual authentication, contracts, … which I realize is probably as huge an effort as doing it all by yourself. 😉

What are other CAs ideas for implementing this? Please feel free to also contact me directly if you rather not discuss on the list. 😊

Kind regards
Roman

From: Servercert-wg <servercert-wg-bounces at cabforum.org<mailto:servercert-wg-bounces at cabforum.org>> On Behalf Of Chris Clements via Servercert-wg
Sent: Montag, 20. Mai 2024 16:30
To: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org<mailto:servercert-wg at cabforum.org>>
Subject: [Servercert-wg] Discussion Period Begins - Ballot SC-067 V3: "Require domain validation and CAA checks to be performed from multiple Network Perspectives"

Purpose of Ballot SC-067 V3:

This Ballot proposes updates to the Baseline Requirements for the Issuance and Management of Publicly-Trusted TLS Server Certificates (i.e., TLS BRs) related to “Multi-Perspective Issuance Corroboration” (“MPIC”).

Background:

- MPIC refers to performing domain validation and CAA checks from multiple Network Perspectives before certificate issuance, as described within the Ballot for the applicable validation methods in TLS BR Sections 3.2.2.4 and 3.2.2.5.

- Not all methods described in TLS BR Sections 3.2.2.4 and 3.2.2.5 will require using MPIC.

- This work was most recently motivated by research presented at Face-to-Face 58 [1] by Princeton University, but has been discussed for years prior as well.

- The goal of this proposal is to make it more difficult for adversaries to successfully launch equally-specific prefix attacks against the domain validation processes described in the TLS BRs.

- Additional background information can be found in an update shared at Face-to-Face 60 [2].

Benefits of Adoption:

- Recent publicly-documented attacks have used BGP hijacks to fool domain control validation and obtain malicious certificates, which led to the impersonation of HTTPS websites [3][4].

- Routing security defenses (e.g., RPKI) can mitigate the risk of global BGP attacks, but localized, equally-specific BGP attacks still pose a significant threat to the Web PKI [5][6].

- Corroborating domain control validation checks from multiple network perspectives (i.e., MPIC) spread across the Internet substantially reduces the threat posed by equally-specific BGP attacks, ensuring the integrity of domain validation and issuance decisions [5][7][8].

- Existing deployments of MPIC at the scale of millions of certificates a day demonstrate the feasibility of this technique at Internet scale [7][9].

Intellectual Property (IP) Disclosure:

- While not a Server Certificate Working Group Member, researchers from Princeton University presented at Face-to-Face 58, provided academic expertise, and highlighted publicly-available peer-reviewed research to support Members in drafting this ballot.

- The Princeton University researchers indicate that they have not filed for any patents relating to their MPIC work and do not plan to do so in the future.

- Princeton University has indicated that it is unable to agree to the CA/Browser Forum IPR agreement because it could encumber inventions invented by researchers not involved in the development of MPIC or with the CA/B Forum.

- Princeton University has instead provided the attached IPR statement. Pursuant to the IPR statement, Princeton University has granted a worldwide royalty free license to the intellectual property in MPIC developed by the researchers and has made representations regarding its lack of knowledge of any other Princeton intellectual property needed to implement MPIC.

- The attached IPR statement has not changed since disclosed in Discussion Round 1.

- For clarity, Princeton University’s IPR statement is NOT intended to replace the Forum’s IPR agreement or allow Princeton to participate in the Forum in any capacity.

- Members seeking legal advice regarding this ballot should consult their own counsel.

Proposal Revision History:

- Pre-Ballot Release #1 (work team artifacts and broader Validation Subcommittee collaboration) [10]

- Pre-Ballot Release #2 [11]

Previous versions of this Ballot:

- Ballot Release #1 [12] (comparing Version 2 to Version 1) [13]. Note, some of the changes represented in the comparison are updates made by other ballots that have since passed (e.g., SC-069).

- Ballot Release #2 [14] (comparing Version 3 to Version 2) [15]. Note, some of the changes represented in the comparison are updates made by other ballots that have since passed (e.g., SC-072).

References:

[1] https://cabforum.org/wp-content/uploads/13-CAB-Forum-face-to-face-multiple-vantage-points.pdf

[2] https://drive.google.com/file/d/1LTwtAwHXcSaPVSsqKQztNJrV2ozHJ7ZL/view?usp=drive_link

[3] https://medium.com/s2wblog/post-mortem-of-klayswap-incident-through-bgp-hijacking-en-3ed7e33de600

[4] https://www.coinbase.com/blog/celer-bridge-incident-analysis

[5] https://www.usenix.org/conference/usenixsecurity23/presentation/cimaszewski

[6] https://www.blackhat.com/docs/us-15/materials/us-15-Gavrichenkov-Breaking-HTTPS-With-BGP-Hijacking-wp.pdf

[7] https://www.usenix.org/conference/usenixsecurity21/presentation/birge-lee

[8] https://www.usenix.org/conference/usenixsecurity18/presentation/birge-lee

[9] https://security.googleblog.com/2023/05/google-trust-services-acme-api_0503894189.html

[10] https://github.com/ryancdickson/staging/pull/6

[11] https://github.com/ryancdickson/staging/pull/8

[12] https://github.com/cabforum/servercert/pull/487

[13] https://github.com/cabforum/servercert/compare/6d10abda8980c6eb941987d3fc26e753e62858c0..5224983ef0a6f94c18808ea3469e7a5ae35746e5

[14] https://github.com/cabforum/servercert/pull/507

[15] https://github.com/cabforum/servercert/compare/5224983ef0a6f94c18808ea3469e7a5ae35746e5..2dcf1a8fe5fc7b6a864b5767ab1db718bc447463

The following motion has been proposed by Chris Clements and Ryan Dickson of Google (Chrome Root Program) and endorsed by Aaron Gable (ISRG / Let’s Encrypt) and Wayne Thayer (Fastly).

— Motion Begins —

This ballot modifies the “Baseline Requirements for the Issuance and Management of Publicly-Trusted TLS Server Certificates” (“Baseline Requirements”), based on Version 2.0.4.

MODIFY the Baseline Requirements as specified in the following Redline:

https://github.com/cabforum/servercert/compare/c4a34fe2292022e0a04ba66b5a85df75907ac2a2..2dcf1a8fe5fc7b6a864b5767ab1db718bc447463

— Motion Ends —

This ballot proposes a Final Maintenance Guideline. The procedure for approval of this ballot is as follows:

Discussion (at least 11 days)

- Start: 2024-05-20 14:30:00 UTC

- End no earlier than: 2024-05-31 14:30:00 UTC

Vote for approval (7 days)

- Start: TBD

- End: TBD

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