CoAP: Echo, Request-Tag, and Token Processing
draft-ietf-core-echo-request-tag-07

Document Type Active Internet-Draft (core WG)
Last updated 2019-09-19
Replaces draft-amsuess-core-repeat-request-tag
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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

   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 March 22, 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

Amsuess, et al.          Expires March 22, 2020                 [Page 1]
Internet-Draft                  CoAP: ERT                 September 2019

   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

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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