The Messaging Layer Security (MLS) Architecture
draft-ietf-mls-architecture-01

Document Type Active Internet-Draft (mls WG)
Last updated 2018-10-22
Replaces draft-omara-mls-architecture
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Send notices to Katriel Cohn-Gordon <me@katriel.co.uk>, Cas Cremers <cas.cremers@cs.ox.ac.uk>, Thyla van der Merwe< thyla.van.der@merwe.tech>, Jon Millican <jmillican@fb.com>, Raphael Robert <raphael@wire.com>
Network Working Group                                           E. Omara
Internet-Draft                                                    Google
Intended status: Informational                             B. Beurdouche
Expires: April 25, 2019                                            INRIA
                                                             E. Rescorla
                                                                 Mozilla
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                                                                 A. Kwon
                                                                     MIT
                                                                A. Duric
                                                                    Wire
                                                        October 22, 2018

            The Messaging Layer Security (MLS) Architecture
                     draft-ietf-mls-architecture-01

Abstract

   This document describes the architecture and requirements for the
   Messaging Layer Security (MLS) protocol.  MLS provides a security
   layer for group messaging applications with from two to a large
   number of clients.  It is meant to protect against eavesdropping,
   tampering, and message forgery.

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
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   This Internet-Draft will expire on April 25, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Omara, et al.            Expires April 25, 2019                 [Page 1]
Internet-Draft              MLS Architecture                October 2018

   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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  General Setting . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Group, Members and Clients  . . . . . . . . . . . . . . .   5
     2.2.  Authentication Service  . . . . . . . . . . . . . . . . .   6
     2.3.  Delivery Service  . . . . . . . . . . . . . . . . . . . .   6
       2.3.1.  Key Storage . . . . . . . . . . . . . . . . . . . . .   7
       2.3.2.  Key Retrieval . . . . . . . . . . . . . . . . . . . .   7
       2.3.3.  Delivery of messages and attachments  . . . . . . . .   7
       2.3.4.  Membership knowledge  . . . . . . . . . . . . . . . .   8
       2.3.5.  Membership and offline members  . . . . . . . . . . .   8
   3.  System Requirements . . . . . . . . . . . . . . . . . . . . .   9
     3.1.  Functional Requirements . . . . . . . . . . . . . . . . .   9
       3.1.1.  Asynchronous Usage  . . . . . . . . . . . . . . . . .   9
       3.1.2.  Recovery After State Loss . . . . . . . . . . . . . .   9
       3.1.3.  Support for Multiple Devices  . . . . . . . . . . . .   9
       3.1.4.  Extensibility / Pluggability  . . . . . . . . . . . .   9
       3.1.5.  Privacy . . . . . . . . . . . . . . . . . . . . . . .  10
       3.1.6.  Federation  . . . . . . . . . . . . . . . . . . . . .  10
       3.1.7.  Compatibility with future versions of MLS . . . . . .  10
     3.2.  Security Requirements . . . . . . . . . . . . . . . . . .  10
       3.2.1.  Connections between Clients and Servers (one-to-one)   10
       3.2.2.  Message Secrecy and Authentication  . . . . . . . . .  10
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
     4.1.  Transport Security Links  . . . . . . . . . . . . . . . .  13
     4.2.  Delivery Service Compromise . . . . . . . . . . . . . . .  13
     4.3.  Authentication Service Compromise . . . . . . . . . . . .  14
     4.4.  Client Compromise . . . . . . . . . . . . . . . . . . . .  14
   5.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  14
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