MQTT-TLS profile of ACE
draft-ietf-ace-mqtt-tls-profile-06

Document Type Active Internet-Draft (ace WG)
Last updated 2020-07-13
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: January 14, 2021                                       Oxbotica
                                                            P. Fremantle
                                                University of Portsmouth
                                                           July 13, 2020

                        MQTT-TLS profile of ACE
                   draft-ietf-ace-mqtt-tls-profile-06

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 January 14, 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
   publication of this document.  Please review these documents

Sengul, et al.          Expires January 14, 2021                [Page 1]
Internet-DraMessage Queuing Telemetry Transport (MQTT)-TLS pr  July 2020

   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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  . . . . . . . . . . . . . . . .   4
   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  . . . . . . . . .  13
         2.2.4.1.  Proof-of-Possession Using a Challenge from the
                   TLS session . . . . . . . . . . . . . . . . . . .  13
         2.2.4.2.  Proof-of-Possession via Broker-generated
                   Challenge/Response  . . . . . . . . . . . . . . .  13
       2.2.5.  Token Validation  . . . . . . . . . . . . . . . . . .  14
       2.2.6.  The Broker's Response to Client Connection Request  .  15
         2.2.6.1.  Unauthorised Request: Authorisation Server
                   Discovery . . . . . . . . . . . . . . . . . . . .  15
         2.2.6.2.  Authorisation Success . . . . . . . . . . . . . .  15
   3.  Authorizing PUBLISH and SUBSCRIBE Messages  . . . . . . . . .  16
     3.1.  PUBLISH Messages from the Publisher Client to the Broker   16
     3.2.  PUBLISH Messages from the Broker to the Subscriber
           Clients . . . . . . . . . . . . . . . . . . . . . . . . .  17
     3.3.  Authorizing SUBSCRIBE Messages  . . . . . . . . . . . . .  17
   4.  Token Expiration and Reauthentication . . . . . . . . . . . .  18
   5.  Handling Disconnections and Retained Messages . . . . . . . .  18
   6.  Reduced Protocol Interactions for MQTT v3.1.1 . . . . . . . .  19
     6.1.  Token Transport . . . . . . . . . . . . . . . . . . . . .  19
     6.2.  Handling Authorization Errors . . . . . . . . . . . . . .  20
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  22
   9.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  23
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