Messaging Layer Security (mls) Internet Drafts

      
 The Messaging Layer Security (MLS) Architecture
 
 draft-ietf-mls-architecture-15.txt
 Date: 03/08/2024
 Authors: Benjamin Beurdouche, Eric Rescorla, Emad Omara, Srinivas Inguva, Alan Duric
 Working Group: Messaging Layer Security (mls)
 The Messaging Layer Security (MLS) protocol (I-D.ietf-mls-protocol) provides a Group Key Agreement protocol for messaging applications. MLS is meant to protect against eavesdropping, tampering, message forgery, and provide Forward Secrecy (FS) and Post-Compromise Security (PCS). This document describes the architecture for using MLS in a general secure group messaging infrastructure and defines the security goals for MLS. It provides guidance on building a group messaging system and discusses security and privacy tradeoffs offered by multiple security mechanisms that are part of the MLS protocol (e.g., frequency of public encryption key rotation). The document also provides guidance for parts of the infrastructure that are not standardized by MLS and are instead left to the application. While the recommendations of this document are not mandatory to follow in order to interoperate at the protocol level, they affect the overall security guarantees that are achieved by a messaging application. This is especially true in the case of active adversaries that are able to compromise clients, the delivery service, or the authentication service.
 The Messaging Layer Security (MLS) Extensions
 
 draft-ietf-mls-extensions-05.txt
 Date: 21/10/2024
 Authors: Raphael Robert
 Working Group: Messaging Layer Security (mls)
 This document describes extensions to the Messaging Layer Security (MLS) protocol. Discussion Venues This note is to be removed before publishing as an RFC. Source for this draft and an issue tracker can be found at https://github.com/mlswg/mls-extensions.
 Flexible Hybrid PQ MLS Combiner
 
 draft-hale-mls-combiner-01.txt
 Date: 26/09/2024
 Authors: Joel, Britta Hale, Marta Mularczyk, Xisen Tian
 Working Group: Messaging Layer Security (mls)
 This document describes a protocol for combining a traditional MLS session with a post-quantum (PQ) MLS session to achieve flexible and efficient hybrid PQ security that amortizes the computational cost of PQ Key Encapsulation Mechanisms and Digital Signature Algorithms. Specifically, we describe how to use the exporter secret of a PQ MLS session, i.e. an MLS session using a PQ ciphersuite, to seed PQ guarantees into an MLS session using a traditional ciphersuite. By supporting on-demand traditional-only key updates (a.k.a. PARTIAL updates) or hybrid-PQ key updates (a.k.a. FULL updates), we can reduce the bandwidth and computational overhead associated with PQ operations while meeting the requirement of frequent key rotations.

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Messaging Layer Security (mls)

WG Name Messaging Layer Security
Acronym mls
Area Security Area (sec)
State Active
Charter charter-ietf-mls-02 Approved
Status update Show Changed 2018-11-07
Document dependencies
Additional resources GitHub organization
Issue tracker
Wiki
Zulip Stream
Personnel Chairs Nick Sullivan, Sean Turner
Area Director Paul Wouters
Secretary Katriel Cohn-Gordon
Mailing list Address mls@ietf.org
To subscribe https://www.ietf.org/mailman/listinfo/mls
Archive https://mailarchive.ietf.org/arch/browse/mls/
Chat Room address https://zulip.ietf.org/#narrow/stream/mls

Charter for Working Group

The Messaging Layer Security (MLS) protocol, RFC 9420, specifies a key
establishment protocol that provides efficient asynchronous group key
establishment with forward secrecy (FS) and post-compromise security (PCS)
for groups in size ranging from two to thousands.

The MLS WG will maintain the protocol and will work on the
following MLS protocol extensions:

  • Support for use of MLS in protocols developed by the MIMI working group
  • Support for new credential types
  • Support for common operational patterns in messaging applications
  • Support for quantum resistance
  • Framework for safe extensibility
  • Detection of lost application messages
  • Support for sending messages to individual members of a group

Many of the extensions to support these features will be included in
draft-ietf-mls-extensions, but some of the extensions will be published in
separate specifications.

Milestones

Date Milestone Associated documents
Dec 2026 Post Quantum security for MLS
Dec 2025 Submit Additional Credentials I-D to IESG as Proposed Standard draft-barnes-mls-addl-creds
Dec 2024 Submit MLS extensions I-D to IESG as Proposed Standard draft-ietf-mls-extensions