The Messaging Layer Security (MLS) Federation
draft-omara-mls-federation-00

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Network Working Group                                           E. Omara
Internet-Draft                                                    Google
Intended status: Informational                                 R. Robert
Expires: September 12, 2019                                         Wire
                                                          March 11, 2019

             The Messaging Layer Security (MLS) Federation
                     draft-omara-mls-federation-00

Abstract

   This document describes how the Messaging Layer Security (MLS) can be
   used in a federated environment where different MLS implementations
   can interoperate by defining the message format for user key
   retrieval.  The document also describes some use cases where
   federation could be useful.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 12, 2019.

Copyright Notice

   Copyright (c) 2019 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Use cases . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Different Delivery Servers  . . . . . . . . . . . . . . .   4
     3.2.  Different client applications . . . . . . . . . . . . . .   4
   4.  Functional Requirements . . . . . . . . . . . . . . . . . . .   4
     4.1.  Delivery service  . . . . . . . . . . . . . . . . . . . .   4
       4.1.1.  Client fanout . . . . . . . . . . . . . . . . . . . .   5
       4.1.2.  Server fanout . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Authentication service  . . . . . . . . . . . . . . . . .   6
   5.  Message format  . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
     6.1.  Version negotiation . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   MLS Architecture draft [MLSARCH] describes the overall MLS system
   architecture assuming the client and servers (Delivery Service and
   Authentication Service) are operated by the same entity.  This
   document describes the minimum changes needed to allow different MLS
   clients operated by the same or different entities to communicate
   with each and explaining The use cases where federation could be
   useful.

   The focus of this document will be the interaction between the client
   and the Delivery Service, specifically how the client retrieves the
   identityKey and InitKeys for another client.  There is no changes
   needed for the Authentication Service.

   Discovering which Delivery service the client communicates with is
   out of the scope of this document.

   The below diagram shows an MLS group where all clients are operated
   under the same deliver service:

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                          +------------+
                         + Delivery     +
                         + Service (DS) +
                          +-----+------+
                       /        +        \             Group