Repeat And Request-Tag
draft-amsuess-core-repeat-request-tag-00

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Last updated 2017-07-01
Replaces draft-amsuess-core-request-tag
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CoRE Working Group                                            C. Amsuess
Internet-Draft                               Energy Harvesting Solutions
Updates: RFC7959 (if approved)                               J. Mattsson
Intended status: Standards Track                             G. Selander
Expires: January 2, 2018                                     Ericsson AB
                                                           July 01, 2017

                         Repeat And Request-Tag
                draft-amsuess-core-repeat-request-tag-00

Abstract

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

   The Repeat 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
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   This Internet-Draft will expire on January 2, 2018.

Amsuess, et al.          Expires January 2, 2018                [Page 1]
Internet-Draft           Repeat And Request-Tag                July 2017

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

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
   ([RFC6347]).  However, for some use cases, additional functionality
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