OSCORE Implementation Guidance
draft-amsuess-lwig-oscore-00

Document Type Active Internet-Draft (individual)
Author Christian Amsüss 
Last updated 2020-04-29
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LWIG                                                           C. Amsüss
Internet-Draft                                             29 April 2020
Intended status: Informational                                          
Expires: 31 October 2020

                     OSCORE Implementation Guidance
                      draft-amsuess-lwig-oscore-00

Abstract

   Object Security for Constrained RESTful Environments (OSCORE) is a
   means of end-to-end protection of short request/response exchanges
   for tiny devices, typically transported using the Constrained
   Application Protocol (CoAP).  This document aims to assist
   implementers in leveraging the optimizations catered for by the
   combination of CoAP and OSCORE, and by generally providing experience
   from earlier implementations.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the LWIG Working Group
   mailing list (lwig@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/lwig/
   (https://mailarchive.ietf.org/arch/browse/lwig/).

   Source for this draft and an issue tracker can be found at
   https://gitlab.com/chrysn/lwig-oscore/ (https://gitlab.com/chrysn/
   lwig-oscore/).

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
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 31 October 2020.

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Copyright Notice

   Copyright (c) 2020 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 publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Context: ACE, LAKE, OSCORE  . . . . . . . . . . . . . . . . .   2
     2.1.  Example compositiions . . . . . . . . . . . . . . . . . .   4
       2.1.1.  Plain ACE-OSCORE  . . . . . . . . . . . . . . . . . .   4
       2.1.2.  ACE with opportunistic LAKE . . . . . . . . . . . . .   5
   3.  Protocol Implementation . . . . . . . . . . . . . . . . . . .   5
     3.1.  Replay, freshness and safety  . . . . . . . . . . . . . .   5
       3.1.1.  Background  . . . . . . . . . . . . . . . . . . . . .   5
       3.1.2.  Optimization  . . . . . . . . . . . . . . . . . . . .   6
       3.1.3.  Implementation  . . . . . . . . . . . . . . . . . . .   7
       3.1.4.  Consequences for replay window recovery using Echo  .   7
   4.  Key IDs . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   5.  HKDFs . . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
     6.1.  Assessment of idempotency . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   9
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   [ See abstract for now ]

2.  Context: ACE, LAKE, OSCORE

   [ Is this LWIG material?  In W3C terminology, this would go into a
   "primer" document. ]

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   When OSCORE was specified, other parts of the ecosystem in which it
   is commonly used were already planned, but not to the extent to be
   fully referernced.  This section gives a bigger picture of how
   surrounding technologies can be combined, with the caveat that some
   of them are still in development:

   *  OSCORE ([RFC8613]):

      -  needs a pre-provisioned key, key identifiers and some other
         details on two communication parties
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