CoAP: Echo, Request-Tag, and Token Processing
draft-ietf-core-echo-request-tag-10
CoRE Working Group C. Amsuess
Internet-Draft
Updates: 7252 (if approved) J. Mattsson
Intended status: Standards Track G. Selander
Expires: January 14, 2021 Ericsson AB
July 13, 2020
CoAP: Echo, Request-Tag, and Token Processing
draft-ietf-core-echo-request-tag-10
Abstract
This document specifies enhancements to the Constrained Application
Protocol (CoAP) that mitigate security issues in particular use
cases. The Echo option enables a CoAP server to verify the freshness
of a request or to force a client to demonstrate reachability at its
claimed network address. The Request-Tag option allows the CoAP
server to match block-wise message fragments belonging to the same
request. This document updates RFC7252 with respect to the client
Token processing requirements, forbidding non-secure reuse of Tokens
to ensure binding of response to request when CoAP is used with
security, and with respect to amplification mitigation, where the use
of Echo is now recommended.
Status of This Memo
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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.
Amsuess, et al. Expires January 14, 2021 [Page 1]
Internet-Draft CoAP: ERT July 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Request Freshness and the Echo Option . . . . . . . . . . . . 4
2.1. Request Freshness . . . . . . . . . . . . . . . . . . . . 4
2.2. The Echo Option . . . . . . . . . . . . . . . . . . . . . 5
2.2.1. Echo Option Format . . . . . . . . . . . . . . . . . 5
2.3. Echo Processing . . . . . . . . . . . . . . . . . . . . . 6
2.4. Applications of the Echo Option . . . . . . . . . . . . . 10
3. Protecting Message Bodies using Request Tags . . . . . . . . 11
3.1. Fragmented Message Body Integrity . . . . . . . . . . . . 11
3.2. The Request-Tag Option . . . . . . . . . . . . . . . . . 12
3.2.1. Request-Tag Option Format . . . . . . . . . . . . . . 12
3.3. Request-Tag Processing by Servers . . . . . . . . . . . . 13
3.4. Setting the Request-Tag . . . . . . . . . . . . . . . . . 14
3.5. Applications of the Request-Tag Option . . . . . . . . . 15
3.5.1. Body Integrity Based on Payload Integrity . . . . . . 15
3.5.2. Multiple Concurrent Block-wise Operations . . . . . . 16
3.5.3. Simplified Block-Wise Handling for Constrained
Proxies . . . . . . . . . . . . . . . . . . . . . . . 17
3.6. Rationale for the Option Properties . . . . . . . . . . . 17
3.7. Rationale for Introducing the Option . . . . . . . . . . 17
3.8. Block2 / ETag Processing . . . . . . . . . . . . . . . . 18
4. Token Processing for Secure Request-Response Binding . . . . 18
4.1. Request-Response Binding . . . . . . . . . . . . . . . . 18
4.2. Updated Token Processing Requirements for Clients . . . . 19
5. Security Considerations . . . . . . . . . . . . . . . . . . . 19
5.1. Token reuse . . . . . . . . . . . . . . . . . . . . . . . 20
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 22
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
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