MQTT-TLS profile of ACE
draft-ietf-ace-mqtt-tls-profile-02

Document Type Active Internet-Draft (ace WG)
Last updated 2019-11-03
Replaces draft-sengul-ace-mqtt-tls-profile
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ACE Working Group                                              C. Sengul
Internet-Draft                                                   Nominet
Intended status: Standards Track                                A. Kirby
Expires: May 5, 2020                                            Oxbotica
                                                            P. Fremantle
                                                University of Portsmouth
                                                        November 2, 2019

                        MQTT-TLS profile of ACE
                   draft-ietf-ace-mqtt-tls-profile-02

Abstract

   This document specifies a profile for the ACE (Authentication and
   Authorization for Constrained Environments) framework to enable
   authorization in an 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 server authentication.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on May 5, 2020.

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
   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
   carefully, as they describe your rights and restrictions with respect

Sengul, et al.             Expires May 5, 2020                  [Page 1]
Internet-Draft           MQTT-TLS profile of ACE           November 2019

   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) . . . . . . .   8
       2.2.1.  Client-Server Authentication over TLS and MQTT  . . .   8
       2.2.2.  authz-info: The Authorization Information Topic . . .   9
       2.2.3.  Transporting Access Token Inside the MQTT CONNECT . .   9
       2.2.4.  Authentication Using AUTH Property  . . . . . . . . .  11
         2.2.4.1.  Proof-of-Possession Using a Challenge from the
                   TLS session . . . . . . . . . . . . . . . . . . .  11
         2.2.4.2.  Proof-of-Possession via Broker-generated
                   Challenge/Response  . . . . . . . . . . . . . . .  12
         2.2.4.3.  Unauthorised Request: Authorisation Server
                   Discovery . . . . . . . . . . . . . . . . . . . .  12
       2.2.5.  Token Validation  . . . . . . . . . . . . . . . . . .  13
       2.2.6.  The Broker's Response to Client Connection Request  .  13
   3.  Authorizing PUBLISH Messages  . . . . . . . . . . . . . . . .  14
     3.1.  PUBLISH Messages from the Publisher Client to the Broker   14
     3.2.  PUBLISH Messages from the Broker to the Subscriber
           Clients . . . . . . . . . . . . . . . . . . . . . . . . .  14
   4.  Authorizing SUBSCRIBE Messages  . . . . . . . . . . . . . . .  15
   5.  Token Expiration and Reauthentication . . . . . . . . . . . .  15
   6.  Handling Disconnections and Retained Messages . . . . . . . .  16
   7.  Reduced Protocol Interactions for MQTT v3.1.1 . . . . . . . .  16
     7.1.  Token Transport . . . . . . . . . . . . . . . . . . . . .  16
     7.2.  Handling Authorization Errors . . . . . . . . . . . . . .  18
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
   10. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  20
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  20
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