CoAP: Echo, Request-Tag, and Token Processing
draft-ietf-core-echo-request-tag-07
CoRE Working Group C. Amsuess
Internet-Draft
Updates: 7252 (if approved) J. Mattsson
Intended status: Standards Track G. Selander
Expires: March 22, 2020 Ericsson AB
September 19, 2019
CoAP: Echo, Request-Tag, and Token Processing
draft-ietf-core-echo-request-tag-07
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. The update to the client Token processing requirements of
RFC 7252 forbids non-secure reuse of Tokens to ensure binding of
responses to requests when CoAP is used with security.
Status of This Memo
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This Internet-Draft will expire on March 22, 2020.
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Amsuess, et al. Expires March 22, 2020 [Page 1]
Internet-Draft CoAP: ERT September 2019
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Request Freshness . . . . . . . . . . . . . . . . . . . . 3
1.2. Fragmented Message Body Integrity . . . . . . . . . . . . 4
1.3. Request-Response Binding . . . . . . . . . . . . . . . . 5
1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. The Echo Option . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Option Format . . . . . . . . . . . . . . . . . . . . . . 7
2.2. Echo Processing . . . . . . . . . . . . . . . . . . . . . 8
2.3. Applications . . . . . . . . . . . . . . . . . . . . . . 10
3. The Request-Tag Option . . . . . . . . . . . . . . . . . . . 11
3.1. Option Format . . . . . . . . . . . . . . . . . . . . . . 12
3.2. Request-Tag Processing by Servers . . . . . . . . . . . . 12
3.3. Setting the Request-Tag . . . . . . . . . . . . . . . . . 13
3.4. Applications . . . . . . . . . . . . . . . . . . . . . . 14
3.4.1. Body Integrity Based on Payload Integrity . . . . . . 14
3.4.2. Multiple Concurrent Block-wise Operations . . . . . . 15
3.4.3. Simplified Block-Wise Handling for Constrained
Proxies . . . . . . . . . . . . . . . . . . . . . . . 16
3.5. Rationale for the Option Properties . . . . . . . . . . . 16
3.6. Rationale for Introducing the Option . . . . . . . . . . 16
4. Block2 / ETag Processing . . . . . . . . . . . . . . . . . . 17
5. Token Processing . . . . . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 17
6.1. Token reuse . . . . . . . . . . . . . . . . . . . . . . . 18
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . 20
9.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Methods for Generating Echo Option Values . . . . . 22
Appendix B. Request-Tag Message Size Impact . . . . . . . . . . 23
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 24
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