Ephemeral Diffie-Hellman Over COSE (EDHOC)
draft-selander-lake-edhoc-01

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Last updated 2020-03-09
Replaces draft-selander-ace-cose-ecdhe
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Network Working Group                                        G. Selander
Internet-Draft                                               J. Mattsson
Intended status: Standards Track                            F. Palombini
Expires: September 10, 2020                                  Ericsson AB
                                                          March 09, 2020

               Ephemeral Diffie-Hellman Over COSE (EDHOC)
                      draft-selander-lake-edhoc-01

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 footprint can be kept very low.

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Selander, et al.       Expires September 10, 2020               [Page 1]
Internet-Draft Ephemeral Diffie-Hellman Over COSE (EDHOC)     March 2020

   to this document.  Code Components extracted from this document must
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Rationale for EDHOC . . . . . . . . . . . . . . . . . . .   4
     1.2.  Terminology and Requirements Language . . . . . . . . . .   5
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   3.  EDHOC Overview  . . . . . . . . . . . . . . . . . . . . . . .   7
     3.1.  Transport and Message Correlation . . . . . . . . . . . .   8
     3.2.  Authentication Keys and Identities  . . . . . . . . . . .   9
     3.3.  Identifiers . . . . . . . . . . . . . . . . . . . . . . .  10
     3.4.  Cipher Suites . . . . . . . . . . . . . . . . . . . . . .  10
     3.5.  Communication/Negotiation of Protocol Features  . . . . .  11
     3.6.  Auxiliary Data  . . . . . . . . . . . . . . . . . . . . .  12
     3.7.  Ephemeral Public Keys . . . . . . . . . . . . . . . . . .  12
     3.8.  Key Derivation  . . . . . . . . . . . . . . . . . . . . .  12
   4.  EDHOC Authenticated with Asymmetric Keys  . . . . . . . . . .  15
     4.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .  15
     4.2.  EDHOC Message 1 . . . . . . . . . . . . . . . . . . . . .  17
     4.3.  EDHOC Message 2 . . . . . . . . . . . . . . . . . . . . .  19
     4.4.  EDHOC Message 3 . . . . . . . . . . . . . . . . . . . . .  22
   5.  EDHOC Authenticated with Symmetric Keys . . . . . . . . . . .  25
     5.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .  25
     5.2.  EDHOC Message 1 . . . . . . . . . . . . . . . . . . . . .  26
     5.3.  EDHOC Message 2 . . . . . . . . . . . . . . . . . . . . .  27
     5.4.  EDHOC Message 3 . . . . . . . . . . . . . . . . . . . . .  28
   6.  Error Handling  . . . . . . . . . . . . . . . . . . . . . . .  28
     6.1.  EDHOC Error Message . . . . . . . . . . . . . . . . . . .  28
   7.  Transferring EDHOC and Deriving an OSCORE Context . . . . . .  30
     7.1.  Transferring EDHOC in CoAP  . . . . . . . . . . . . . . .  30
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  33
     8.1.  Security Properties . . . . . . . . . . . . . . . . . . .  33
     8.2.  Cryptographic Considerations  . . . . . . . . . . . . . .  34
     8.3.  Cipher Suites . . . . . . . . . . . . . . . . . . . . . .  35
     8.4.  Unprotected Data  . . . . . . . . . . . . . . . . . . . .  35
     8.5.  Denial-of-Service . . . . . . . . . . . . . . . . . . . .  36
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