Echo and Request-Tag
draft-ietf-core-echo-request-tag-00

Document Type Active Internet-Draft (core WG)
Last updated 2017-10-31 (latest revision 2017-10-30)
Replaces draft-amsuess-core-repeat-request-tag
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CoRE Working Group                                            C. Amsuess
Internet-Draft                               Energy Harvesting Solutions
Updates: 7959 (if approved)                                  J. Mattsson
Intended status: Standards Track                             G. Selander
Expires: May 3, 2018                                         Ericsson AB
                                                        October 30, 2017

                          Echo and Request-Tag
                  draft-ietf-core-echo-request-tag-00

Abstract

   This document defines two optional extensions to the Constrained
   Application Protocol (CoAP): the Echo option and the Request-Tag
   option.  Each of these options when integrity protected, such as with
   DTLS or OSCORE, protects against certain attacks on CoAP message
   exchanges.

   The Echo option enables a CoAP server to verify the freshness of a
   request by requiring the CoAP client to make another request and
   include a server-provided challenge.  The Request-Tag option allows
   the CoAP server to match message fragments belonging to the same
   request message, fragmented using the CoAP Block-Wise Transfer
   mechanism.  This document also specifies additional processing
   requirements on Block1 and Block2 options.

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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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 3, 2018.

Amsuess, et al.            Expires May 3, 2018                  [Page 1]
Internet-Draft            Echo and Request-Tag              October 2017

Copyright Notice

   Copyright (c) 2017 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Request Freshness . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Fragmented Message Body Integrity . . . . . . . . . . . .   3
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  The Echo Option . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Option Format . . . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Echo Processing . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  Applications  . . . . . . . . . . . . . . . . . . . . . .   7
   3.  The Request-Tag Option  . . . . . . . . . . . . . . . . . . .   8
     3.1.  Option Format . . . . . . . . . . . . . . . . . . . . . .   9
     3.2.  Request-Tag Processing  . . . . . . . . . . . . . . . . .  10
     3.3.  Applications  . . . . . . . . . . . . . . . . . . . . . .  11
       3.3.1.  Body Integrity Based on Payload Integrity . . . . . .  11
       3.3.2.  Multiple Concurrent Blockwise Operations  . . . . . .  12
   4.  Block2 / ETag Processing  . . . . . . . . . . . . . . . . . .  13
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Appendix A.  Performance Impact When Using the Echo Option  . . .  14
   Appendix B.  Request-Tag Message Size Impact  . . . . . . . . . .  15
   Appendix C.  Change Log . . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   The initial CoAP suite of specifications ([RFC7252], [RFC7641],
   [RFC7959]) was designed with the assumption that security could be
   provided on a separate layer, in particular by using DTLS
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