MQTT-TLS profile of ACE
draft-ietf-ace-mqtt-tls-profile-06
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
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This Internet-Draft will expire on January 14, 2021.
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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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