Message Queuing Telemetry Transport (MQTT)-TLS profile of Authentication and Authorization for Constrained Environments (ACE) Framework
draft-ietf-ace-mqtt-tls-profile-07

Document Type Active Internet-Draft (ace WG)
Last updated 2020-09-22 (latest revision 2020-08-25)
Replaces draft-sengul-ace-mqtt-tls-profile
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ACE Working Group                                              C. Sengul
Internet-Draft                                         Brunel University
Intended status: Standards Track                                A. Kirby
Expires: February 26, 2021                                      Oxbotica
                                                            P. Fremantle
                                                University of Portsmouth
                                                         August 25, 2020

Message Queuing Telemetry Transport (MQTT)-TLS profile of Authentication
     and Authorization for Constrained Environments (ACE) Framework
                   draft-ietf-ace-mqtt-tls-profile-07

Abstract

   This document specifies a profile for the ACE (Authentication and
   Authorization for Constrained Environments) framework to enable
   authorization in an Message Queuing Telemetry Transport (MQTT)-based
   publish-subscribe messaging system.  Proof-of-possession keys, bound
   to OAuth2.0 access tokens, are used to authenticate and authorize
   MQTT Clients.  The protocol relies on TLS for confidentiality and
   MQTT server (broker) authentication.

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 February 26, 2021.

Copyright Notice

   Copyright (c) 2020 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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of

Sengul, et al.          Expires February 26, 2021               [Page 1]
Internet-Draft           MQTT-TLS profile of ACE             August 2020

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     1.2.  ACE-Related Terminology . . . . . . . . . . . . . . . . .   4
     1.3.  MQTT-Related Terminology  . . . . . . . . . . . . . . . .   5
   2.  Authorizing Connection Requests . . . . . . . . . . . . . . .   7
     2.1.  Client Token Request to the Authorization Server (AS) . .   8
     2.2.  Client Connection Request to the Broker (C) . . . . . . .   9
       2.2.1.  Client-Server Authentication over TLS and MQTT  . . .   9
       2.2.2.  authz-info: The Authorization Information Topic . . .  10
       2.2.3.  Transporting Access Token Inside the MQTT CONNECT . .  11
       2.2.4.  Authentication Using AUTH Property  . . . . . . . . .  14
         2.2.4.1.  Proof-of-Possession Using a Challenge from the
                   TLS session . . . . . . . . . . . . . . . . . . .  14
         2.2.4.2.  Proof-of-Possession via Broker-generated
                   Challenge/Response  . . . . . . . . . . . . . . .  14
       2.2.5.  Token Validation  . . . . . . . . . . . . . . . . . .  15
       2.2.6.  The Broker's Response to Client Connection Request  .  16
         2.2.6.1.  Unauthorised Request: Authorisation Server
                   Discovery . . . . . . . . . . . . . . . . . . . .  16
         2.2.6.2.  Authorisation Success . . . . . . . . . . . . . .  16
   3.  Authorizing PUBLISH and SUBSCRIBE Messages  . . . . . . . . .  16
     3.1.  PUBLISH Messages from the Publisher Client to the Broker   17
     3.2.  PUBLISH Messages from the Broker to the Subscriber
           Clients . . . . . . . . . . . . . . . . . . . . . . . . .  18
     3.3.  Authorizing SUBSCRIBE Messages  . . . . . . . . . . . . .  18
   4.  Token Expiration and Reauthentication . . . . . . . . . . . .  18
   5.  Handling Disconnections and Retained Messages . . . . . . . .  19
   6.  Reduced Protocol Interactions for MQTT v3.1.1 . . . . . . . .  19
     6.1.  Token Transport . . . . . . . . . . . . . . . . . . . . .  20
     6.2.  Handling Authorization Errors . . . . . . . . . . . . . .  21
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  22
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  23
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