CBOR Object Signing and Encryption (COSE)
RFC 8152

Document Type RFC - Proposed Standard (July 2017; Errata)
Last updated 2017-07-12
Replaces draft-schaad-cose-msg
Stream IETF
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Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Göran Selander
Shepherd write-up Show (last changed 2016-08-14)
IESG IESG state RFC 8152 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Kathleen Moriarty
Send notices to "Goeran Selander" <goran.selander@ericsson.com>
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                         J. Schaad
Request for Comments: 8152                                August Cellars
Category: Standards Track                                      July 2017
ISSN: 2070-1721

               CBOR Object Signing and Encryption (COSE)

Abstract

   Concise Binary Object Representation (CBOR) is a data format designed
   for small code size and small message size.  There is a need for the
   ability to have basic security services defined for this data format.
   This document defines the CBOR Object Signing and Encryption (COSE)
   protocol.  This specification describes how to create and process
   signatures, message authentication codes, and encryption using CBOR
   for serialization.  This specification additionally describes how to
   represent cryptographic keys using CBOR.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc8152.

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
   Provisions Relating to IETF Documents
   (http://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.

Schaad                       Standards Track                    [Page 1]
RFC 8152        CBOR Object Signing and Encryption (COSE)      July 2017

Table of Contents

   1. Introduction ....................................................4
      1.1. Design Changes from JOSE ...................................5
      1.2. Requirements Terminology ...................................6
      1.3. CBOR Grammar ...............................................6
      1.4. CBOR-Related Terminology ...................................7
      1.5. Document Terminology .......................................8
   2. Basic COSE Structure ............................................8
   3. Header Parameters ..............................................10
      3.1. Common COSE Headers Parameters ............................12
   4. Signing Objects ................................................16
      4.1. Signing with One or More Signers ..........................16
      4.2. Signing with One Signer ...................................18
      4.3. Externally Supplied Data ..................................19
      4.4. Signing and Verification Process ..........................20
      4.5. Computing Counter Signatures ..............................22
   5. Encryption Objects .............................................22
      5.1. Enveloped COSE Structure ..................................23
           5.1.1. Content Key Distribution Methods ...................24
      5.2. Single Recipient Encrypted ................................25
      5.3. How to Encrypt and Decrypt for AEAD Algorithms ............26
      5.4. How to Encrypt and Decrypt for AE Algorithms ..............28
   6. MAC Objects ....................................................29
      6.1. MACed Message with Recipients .............................30
      6.2. MACed Messages with Implicit Key ..........................31
      6.3. How to Compute and Verify a MAC ...........................32
   7. Key Objects ....................................................33
      7.1. COSE Key Common Parameters ................................34
   8. Signature Algorithms ...........................................37
      8.1. ECDSA .....................................................38
           8.1.1. Security Considerations ............................40
      8.2. Edwards-Curve Digital Signature Algorithms (EdDSAs) .......40
           8.2.1. Security Considerations ............................41
   9. Message Authentication Code (MAC) Algorithms ...................42
      9.1. Hash-Based Message Authentication Codes (HMACs) ...........42
           9.1.1. Security Considerations ............................44
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