More Instant Messaging Interoperability K. Kohbrok Internet-Draft R. Robert Intended status: Informational Phoenix R&D Expires: 23 April 2026 20 October 2025 MIMI Identifiers draft-kohbrok-mimi-identifiers-00 Abstract TODO Abstract About This Document This note is to be removed before publishing as an RFC. The latest revision of this draft can be found at https://kkohbrok.github.io/draft-kohbrok-mimi-identifiers/draft- kohbrok-mimi-identifiers.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-kohbrok-mimi- identifiers/. Discussion of this document takes place on the More Instant Messaging Interoperability Working Group mailing list (mailto:mimi@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/mimi/. Subscribe at https://www.ietf.org/mailman/listinfo/mimi/. Source for this draft and an issue tracker can be found at https://github.com/kkohbrok/draft-kohbrok-mimi-identifiers. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 23 April 2026. Kohbrok & Robert Expires 23 April 2026 [Page 1] Internet-Draft MIMI Identifiers October 2025 Copyright Notice Copyright (c) 2025 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Identifier types . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Identifiers for connection establishment . . . . . . . . 2 2.2. Administrative identifiers . . . . . . . . . . . . . . . 3 2.3. Display names (decorative identifiers) . . . . . . . . . 3 3. Proposal for MIMI . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Connection establishment . . . . . . . . . . . . . . . . 4 3.2. Administrative identifiers . . . . . . . . . . . . . . . 4 3.3. Display names . . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Normative References . . . . . . . . . . . . . . . . . . . . 4 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction * MIMI currently doesn't make assumptions about names beyond the URI format introduced in [I-D.draft-ietf-mimi-protocol] * Different messaging applications use different schemes * MIMI should be able to support at least the most widely used ones 2. Identifier types 2.1. Identifiers for connection establishment * Globally unique * User-facing Kohbrok & Robert Expires 23 April 2026 [Page 2] Internet-Draft MIMI Identifiers October 2025 * Often chosen by user * Multiple identifiers per user possible * User can add/delete identifiers dynamically * Examples: - Phone numbers - Signal-style usernames - Matrix-style usernames - Administrative identifiers 2.2. Administrative identifiers * Globally unique * Generally not user-facing * Generally not chosen-facing * Can be provider-generated * Server might not be able to link admin to connection establishment identifiers * Immutable * Examples - UUIDs - Matrix-style usernames 2.3. Display names (decorative identifiers) * Not globally unique * Not necessarily visible to provider * User-facing * User-chosen Kohbrok & Robert Expires 23 April 2026 [Page 3] Internet-Draft MIMI Identifiers October 2025 3. Proposal for MIMI 3.1. Connection establishment * Multiple options for connection establishment identifiers - Phone numbers (draft WIP) - Usernames (user chosen names, potentially with format restrictions) * No requirement for providers to be able to link connection establishment identifiers with administrative identifiers * Ephemeral identifiers should be allowed 3.2. Administrative identifiers * Should be unique within domain of provider * Should be immutable * No other requirement w.r.t. format, i.e. both Matrix-style and UUIDs allowed * No requirement for user-readability * These are used for authentication and are included in MLS credentials 3.3. Display names * No strict requirement for hub/provider to have access to display names, may be subject to policy 4. Security Considerations TODO Security 5. IANA Considerations This document has no IANA actions. 6. Normative References [I-D.draft-ietf-mimi-protocol] Barnes, R., Hodgson, M., Kohbrok, K., Mahy, R., Ralston, T., and R. Robert, "More Instant Messaging Kohbrok & Robert Expires 23 April 2026 [Page 4] Internet-Draft MIMI Identifiers October 2025 Interoperability (MIMI) using HTTPS and MLS", Work in Progress, Internet-Draft, draft-ietf-mimi-protocol-05, 20 October 2025, . Acknowledgments TODO acknowledge. Authors' Addresses Konrad Kohbrok Phoenix R&D Email: konrad@ratchet.ing Raphael Robert Phoenix R&D Email: ietf@raphaelrobert.com Kohbrok & Robert Expires 23 April 2026 [Page 5]