The Messaging Layer Security (MLS) Architecture
draft-ietf-mls-architecture-04
Network Working Group E. Omara
Internet-Draft Google
Intended status: Informational B. Beurdouche
Expires: July 29, 2020 INRIA
E. Rescorla
Mozilla
S. Inguva
Twitter
A. Kwon
MIT
A. Duric
Wire
January 26, 2020
The Messaging Layer Security (MLS) Architecture
draft-ietf-mls-architecture-04
Abstract
This document describes the reference architecture, functional and
security 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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This Internet-Draft will expire on July 29, 2020.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
Omara, et al. Expires July 29, 2020 [Page 1]
Internet-Draft MLS Architecture January 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. General Setting . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Group, Members and Clients . . . . . . . . . . . . . . . 5
2.2. Authentication Service . . . . . . . . . . . . . . . . . 6
2.3. Delivery Service . . . . . . . . . . . . . . . . . . . . 7
2.3.1. Key Storage . . . . . . . . . . . . . . . . . . . . . 8
2.3.2. Key Retrieval . . . . . . . . . . . . . . . . . . . . 8
2.3.3. Delivery of messages and attachments . . . . . . . . 8
2.3.4. Membership knowledge . . . . . . . . . . . . . . . . 9
2.3.5. Membership and offline members . . . . . . . . . . . 10
3. System Requirements . . . . . . . . . . . . . . . . . . . . . 10
3.1. Functional Requirements . . . . . . . . . . . . . . . . . 10
3.1.1. Asynchronous Usage . . . . . . . . . . . . . . . . . 10
3.1.2. Recovery After State Loss . . . . . . . . . . . . . . 10
3.1.3. Support for Multiple Devices . . . . . . . . . . . . 11
3.1.4. Extensibility / Pluggability . . . . . . . . . . . . 11
3.1.5. Privacy . . . . . . . . . . . . . . . . . . . . . . . 11
3.1.6. Federation . . . . . . . . . . . . . . . . . . . . . 11
3.1.7. Compatibility with future versions of MLS . . . . . . 12
3.2. Security Requirements . . . . . . . . . . . . . . . . . . 12
3.2.1. Connections between Clients and Servers (one-to-one) 12
3.2.2. Message Secrecy and Authentication . . . . . . . . . 12
4. Security Considerations . . . . . . . . . . . . . . . . . . . 15
4.1. Transport Security Links . . . . . . . . . . . . . . . . 15
4.2. Delivery Service Compromise . . . . . . . . . . . . . . . 15
4.3. Authentication Service Compromise . . . . . . . . . . . . 16
4.4. Client Compromise . . . . . . . . . . . . . . . . . . . . 16
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
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