CBOR Object Signing and Encryption (COSE)
draft-ietf-cose-msg-14

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Document Type Active Internet-Draft (cose WG)
Last updated 2016-06-23
Replaces draft-schaad-cose-msg
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COSE Working Group                                             J. Schaad
Internet-Draft                                            August Cellars
Intended status: Standards Track                           June 23, 2016
Expires: December 25, 2016

               CBOR Object Signing and Encryption (COSE)
                         draft-ietf-cose-msg-14

Abstract

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

Contributing to this document

   The source for this draft is being maintained in GitHub.  Suggested
   changes should be submitted as pull requests at <https://github.com/
   cose-wg/cose-spec>.  Instructions are on that page as well.
   Editorial changes can be managed in GitHub, but any substantial
   issues need to be discussed on the COSE mailing list.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://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 December 25, 2016.

Schaad                  Expires December 25, 2016               [Page 1]
Internet-Draft  CBOR Object Signing and Encryption (COSE)      June 2016

Copyright Notice

   Copyright (c) 2016 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.

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  . . . . . . . . . . . . . . . . . .   7
   2.  Basic COSE Structure  . . . . . . . . . . . . . . . . . . . .   8
   3.  Header Parameters . . . . . . . . . . . . . . . . . . . . . .  10
     3.1.  Common COSE Headers Parameters  . . . . . . . . . . . . .  11
   4.  Signing Objects . . . . . . . . . . . . . . . . . . . . . . .  15
     4.1.  Signing with One or More Signers  . . . . . . . . . . . .  15
     4.2.  Signing with One Signer . . . . . . . . . . . . . . . . .  17
     4.3.  Externally Supplied Data  . . . . . . . . . . . . . . . .  18
     4.4.  Signing and Verification Process  . . . . . . . . . . . .  19
     4.5.  Computing Counter Signatures  . . . . . . . . . . . . . .  20
   5.  Encryption Objects  . . . . . . . . . . . . . . . . . . . . .  21
     5.1.  Enveloped COSE Structure  . . . . . . . . . . . . . . . .  21
       5.1.1.  Recipient Algorithm Classes . . . . . . . . . . . . .  23
     5.2.  Single Recipient Encrypted  . . . . . . . . . . . . . . .  24
     5.3.  Encryption Algorithm for AEAD algorithms  . . . . . . . .  24
     5.4.  Encryption algorithm for AE algorithms  . . . . . . . . .  26
   6.  MAC Objects . . . . . . . . . . . . . . . . . . . . . . . . .  28
     6.1.  MACed Message with Recipients . . . . . . . . . . . . . .  28
     6.2.  MACed Messages with Implicit Key  . . . . . . . . . . . .  29
     6.3.  How to compute and verify a MAC . . . . . . . . . . . . .  30
   7.  Key Objects . . . . . . . . . . . . . . . . . . . . . . . . .  31
     7.1.  COSE Key Common Parameters  . . . . . . . . . . . . . . .  32
   8.  Signature Algorithms  . . . . . . . . . . . . . . . . . . . .  35
     8.1.  ECDSA . . . . . . . . . . . . . . . . . . . . . . . . . .  36
       8.1.1.  Security Considerations . . . . . . . . . . . . . . .  37
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