Messaging Layer Security Architecture
draft-omara-mls-architecture-01

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Last updated 2018-02-07
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Network Working Group                                           E. Omara
Internet-Draft                                                    Google
Intended status: Informational                             B. Beurdouche
Expires: August 11, 2018                                           INRIA
                                                             E. Rescorla
                                                                 Mozilla
                                                               S. Inguva
                                                                 Twitter
                                                                 A. Kwon
                                                                     MIT
                                                                A. Duric
                                                                    Wire
                                                       February 07, 2018

                 Messaging Layer Security Architecture
                    draft-omara-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

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 11, 2018.

Copyright Notice

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

Omara, et al.            Expires August 11, 2018                [Page 1]
Internet-Draft              MLS Architecture               February 2018

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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 . . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Functional Requirements . . . . . . . . . . . . . . . . .   8
       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 . . . . . . . . . . . . . . . . . . . . . . .   9
       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 . . . . . . . . . . . .  13
     4.4.  Client Compromise . . . . . . . . . . . . . . . . . . . .  14
   5.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  14
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