Session Date/Time: 28 Jul 2023 00:00

mls

Summary

The MLS meeting covered several topics, including newly published RFCs, extensions to credential types, post-quantum cipher suites, self-removal proposals, and guidance on designing safe extensions. There was discussion and support for adopting several drafts, including the additional credentials draft and the post-quantum cipher suites draft. The meeting concluded with a discussion on the need to re-charter the working group.

Key Discussion Points

RFC Publication: MLS RFC 9420 has been published.
Additional Credentials: Discussion on new credential types, including user info VC, multi-credential, and weak multi-credential. User info VC ties into OpenID for easier user authentication.
Post-Quantum Cipher Suites: Proposal for a hybrid post-quantum (Kyber + x25519) cipher suite to protect against the harvest now decrypt later attack. Discussions on the appropriate symmetric key sizes (AES-128 vs AES-256).
Self-Removal Proposals: Proposal for a self-removal mechanism to address the challenges of leaving groups with frequent joins and removes due to external commits invalidating remove proposals.
MLS Extensions: Update on the MLS extensions document, including guidance on designing safe extensions and a concrete API for extensions. Discussion of potential extensions, including deniability modes, mini-related extensions, and application messages from external senders.
Guardianship for MLS: Presentation of a concept for guardianship in MLS, enabling users with multiple devices operating in limited mode to benefit from MLS security guarantees. Discussions centered on design choices and the trade-offs in security and traceability.

Decisions and Action Items

Additional Credentials Draft Adoption: The group unanimously agreed to adopt the additional credentials draft.
Post-Quantum Cipher Suites Draft Adoption: The group agreed to adopt the post-quantum cipher suites draft.
Self-Removal Proposal: The group agreed to incorporate the self-removal proposal into the extensions draft via a PR.
Rechartering: The chairs will take an action item to begin the re-chartering process for the working group, figuring out what to prioritize and setting milestones.

Next Steps

Richard will continue editorial work on the detector document.
Implementation and review of the adopted drafts (additional credentials and post-quantum cipher suites).
Submit a PR to incorporate the self-removal proposal into the extensions draft.
Chairs to initiate the re-chartering process, prioritizing work and setting milestones.
The "Guardianship for MLS" team will write an Internet Draft.