IETF 122 - MIMI WG Meeting Notes

Date: March 19, 2025

Adoption Call for draft-interop-mimi-discovery-requirements

• Richard Barnes: Minor comments but supports adoption.
• Eric Rescorla: Reviewed the discovery requirements document and
  supports adoption. Acknowledges it’s not perfect but considers it a
  good start.
• Alissa Cooper: Conclusion: The document is considered
  adopted!

Result: Adopted!

Richard Barnes - Presentation on draft-ietf-mimi-arch

• Review on the topic.

Rohan Mahy - Presentation on MIMI Protocol

• Three PRs to review:

Download Proxy PR

• Raphael: Too many options are being provided.
• Raphael: Suggested introducing an authentication mechanism to
  enforce quotas.
• Marvin: Opposes recommending OHTTP.
• Alissa: Agrees that there are too many options; confused about
  the recommendations.
• Daniel: Shares Alissa’s concerns and suggests clearly defining
  that the hub is "in the hook."
• Rohan: Requests that reviews be submitted to the mailing list or
  in the issue tracker.

Review Issues

• Call for review: Issues #26 and #25 to be closed.
• Issue #38 ("Knocks") – Deferred for later discussion.
  • Raphael: Notes that there was some consensus from last time,
    and these decisions need to be included.

Issue #23: Arbitrary State

• The new MLS AppDataUpdate can support this.

Raphael Presenting: Pseudonymous Credentials

Working Items

• MMRs require a well-defined concept of a "Connection," which is
  not yet fully specified in MIMI.
• Synchronizing decryption keys via TreeWrap.
• KeyPackage for MMRs publication is not yet specified but should
  be straightforward.
• Pre-authorization remains an open question.

Discussion Points

• Rohan: For the external commit case, can external joiners obtain
  real identities?
• Raphael: External commits are generally possible, but for
  knocks, they are not.
• Rohan: The concern is whether it's acceptable for someone to
  join via external commit without receiving all information. Wants to
  see if there’s a strong argument against this.
• Raphael: Agrees; it makes sense that someone can join a room
  without immediately seeing all members. Proposes improving this by
  finding a better way to share keying material.

Rohan: Continue on the Presentation

• Can this be ready for WG Last Call by Madrid?
  • Alissa: More people need to implement this!
  • Richard: Agrees.
  • Rohan: Some code exists, but more implementation is needed.
  • Raphael: Implementation of some parts of the protocol is
    underway, but the draft itself has yet to be implemented.
  • Richard: Acknowledges progress but suggests involving
    students or hackathon participants to assist with
    implementation, similar to MLS efforts.
  • Timo: Asks about peering relations within the group.
    • Rohan: Refers to the main architecture document for
      details.

Rohan: MIMI Contents Presentation

• Changes since -05.
• Issues that need to be fixed—if there are no objections, they will
  be closed (can be reopened later).
• Richard: It's not acceptable to close issues without considering
  time zones.
• Daniel: Nested attachments are not interoperable.
• Timo: Multipart attachments seem excessive.
• Marvin: Some features can be removed, but we generally need this
  functionality.

Next Steps:

• Immediately start a WG Last Call.
• Close the open issues.
• Note: Delivery reports need more review—should they be moved to
  another draft?

Discussion:

• Alissa: Let's have an implementation first.
• Richard: Agreed.
• Timo (in chat): I'd like more time on MIMI-Content. When
  implementing, I found additional small issues with Markdown.

Rohan: Updates on Room Policies

• Rohan: There is an implementation in progress, expected to be
  open-sourced this summer.
• Timo: Will implement room policies soon.

Rohan: MIMI Identity

• Do we need this draft? Currently more of a survey of the problem
  space.

Discussion:

• Richard: The analysis is confusing. We do need identifiers and a
  base credential type. The draft may need to be rebooted.

Brendan McMillion: Presentation on draft-mcmillion-mls-subgroups

Call for Adoption

Discussion:

• Rohan: If Alice has multiple identities, this model does not
  reflect that well.

• Raphael:

  • There are two more drafts in MLSWG.
  • No changes are required in wire format, but additional
    modifications are needed for MIMI.
  • Regardless of which draft we adopt, privacy concerns remain—we
    do not know which clients emit updates or which devices are
    active.
  • A policy could mandate updates.
  • Ideally, we should use one of these drafts in MIMI, but
    implementation remains uncertain.
  • We need a mechanism to securely roll out clients.

• Mojtaba: The subgroup name is incorrect; it should be in
  MLSWG. The identity issue is significant, and the server needs
  to play a role.

• Rohan: Love the idea. Regarding functionality, servers do not
  store messages indefinitely. If I go on vacation with my phone on
  but my laptop off, what happens to those messages?
• Daniel: Thanks for the discussion. MLS should drive how we move
  forward and decide which draft to adopt.
• Raphael:
• We should discuss this in MLSWG, it will helps the MLS Group to
  be more efficient.

• Tim:

  • MIMI is concerned about the problem, but there is another
    related issue in the MLS WG. This draft should be discussed in
    MLSWG.

• Brendan:

  • Already presented this to MLSWG, which referred it to
    MIMI.

• Rohan:

  • MIMI also needs to do additional work, but the necessary
    primitives should be handled in MLS.

• Raphael:

  • Brendan is right—not changing the wire format is a good
    approach, but subgroups require modifications in MIMI.

• Brendan:

  • Disagree. Based on the slides, those changes are not necessary.

• Raphael:

  • Still not convinced.

• Brendan:

• would like to have show hands

• Tim:

  • it was clear to go for MLSWG

• Orie:

  • we can check on the MIMI List, still not sure what's the right
    path, thanks for the discussion, I'll be available for more
    discussion

• Rohan:

  • the changes of wire format are not the case, the case is on MLS

Result:

• Will talke to our AD and will be communicated to Brendan later