Ephemeral Diffie-Hellman Over COSE (EDHOC)
draft-ietf-lake-edhoc-05

Document Type Active Internet-Draft (lake WG)
Authors Göran Selander  , John Preuß Mattsson  , Francesca Palombini 
Last updated 2021-02-22
Replaces draft-selander-lake-edhoc
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Network Working Group                                        G. Selander
Internet-Draft                                               J. Mattsson
Intended status: Standards Track                            F. Palombini
Expires: 26 August 2021                                      Ericsson AB
                                                        22 February 2021

               Ephemeral Diffie-Hellman Over COSE (EDHOC)
                        draft-ietf-lake-edhoc-05

Abstract

   This document specifies Ephemeral Diffie-Hellman Over COSE (EDHOC), a
   very compact and lightweight authenticated Diffie-Hellman key
   exchange with ephemeral keys.  EDHOC provides mutual authentication,
   perfect forward secrecy, and identity protection.  EDHOC is intended
   for usage in constrained scenarios and a main use case is to
   establish an OSCORE security context.  By reusing COSE for
   cryptography, CBOR for encoding, and CoAP for transport, the
   additional code size can be kept very low.

Status of This Memo

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   This Internet-Draft will expire on 26 August 2021.

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   Please review these documents carefully, as they describe your rights
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Selander, et al.         Expires 26 August 2021                 [Page 1]
Internet-Draft  Ephemeral Diffie-Hellman Over COSE (EDHO   February 2021

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Motivation  . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Use of EDHOC  . . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Message Size Examples . . . . . . . . . . . . . . . . . .   6
     1.4.  Document Structure  . . . . . . . . . . . . . . . . . . .   6
     1.5.  Terminology and Requirements Language . . . . . . . . . .   6
   2.  EDHOC Outline . . . . . . . . . . . . . . . . . . . . . . . .   7
   3.  Protocol Elements . . . . . . . . . . . . . . . . . . . . . .   9
     3.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .   9
     3.2.  Method and Correlation  . . . . . . . . . . . . . . . . .   9
       3.2.1.  Method  . . . . . . . . . . . . . . . . . . . . . . .  10
       3.2.2.  Connection Identifiers  . . . . . . . . . . . . . . .  10
       3.2.3.  Transport . . . . . . . . . . . . . . . . . . . . . .  11
       3.2.4.  Message Correlation . . . . . . . . . . . . . . . . .  11
     3.3.  Authentication Parameters . . . . . . . . . . . . . . . .  11
       3.3.1.  Authentication Keys . . . . . . . . . . . . . . . . .  11
       3.3.2.  Identities  . . . . . . . . . . . . . . . . . . . . .  12
       3.3.3.  Authentication Credentials  . . . . . . . . . . . . .  13
       3.3.4.  Identification of Credentials . . . . . . . . . . . .  14
     3.4.  Cipher Suites . . . . . . . . . . . . . . . . . . . . . .  15
     3.5.  Ephemeral Public Keys . . . . . . . . . . . . . . . . . .  17
     3.6.  Auxiliary Data  . . . . . . . . . . . . . . . . . . . . .  17
     3.7.  Communication of Protocol Features  . . . . . . . . . . .  18
   4.  Key Derivation  . . . . . . . . . . . . . . . . . . . . . . .  18
     4.1.  EDHOC-Exporter Interface  . . . . . . . . . . . . . . . .  20
   5.  Message Formatting and Processing . . . . . . . . . . . . . .  21
     5.1.  Encoding of bstr_identifier . . . . . . . . . . . . . . .  21
     5.2.  EDHOC Message 1 . . . . . . . . . . . . . . . . . . . . .  22
       5.2.1.  Formatting of Message 1 . . . . . . . . . . . . . . .  22
       5.2.2.  Initiator Processing of Message 1 . . . . . . . . . .  23
       5.2.3.  Responder Processing of Message 1 . . . . . . . . . .  23
     5.3.  EDHOC Message 2 . . . . . . . . . . . . . . . . . . . . .  24
       5.3.1.  Formatting of Message 2 . . . . . . . . . . . . . . .  24
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