CoAP: Echo, Request-Tag, and Token Processing
draft-ietf-core-echo-request-tag-08

Document Type Active Internet-Draft (core WG)
Last updated 2019-11-04
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: May 7, 2020                                         Ericsson AB
                                                       November 04, 2019

             CoAP: Echo, Request-Tag, and Token Processing
                  draft-ietf-core-echo-request-tag-08

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 May 7, 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 May 7, 2020                  [Page 1]
Internet-Draft                  CoAP: ERT                  November 2019

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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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 . . . . . . . . . . . . . . . . . . . . . . .  16
     3.6.  Rationale for the Option Properties . . . . . . . . . . .  16
     3.7.  Rationale for Introducing the Option  . . . . . . . . . .  17
     3.8.  Block2 / ETag Processing  . . . . . . . . . . . . . . . .  17
   4.  Token Processing for Secure Request-Response Binding  . . . .  18
     4.1.  Request-Response Binding  . . . . . . . . . . . . . . . .  18
     4.2.  Updated Token Processing Requirements for Clients . . . .  18
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
     5.1.  Token reuse . . . . . . . . . . . . . . . . . . . . . . .  20
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  21
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  22
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  22
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  22
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