CBOR Object Signing and Encryption (COSE): Initial Algorithms
draft-ietf-cose-rfc8152bis-algs-02

Document Type Active Internet-Draft (cose WG)
Last updated 2019-03-11
Replaces draft-schaad-cose-rfc8152bis-algs
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COSE Working Group                                             J. Schaad
Internet-Draft                                            August Cellars
Obsoletes: 8152 (if approved)                             March 11, 2019
Intended status: Standards Track
Expires: September 12, 2019

     CBOR Object Signing and Encryption (COSE): Initial Algorithms
                   draft-ietf-cose-rfc8152bis-algs-02

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.  COSE additionally describes how to represent
   cryptographic keys using CBOR.

   In this specification the conventions for the use of a number of
   cryptographic algorithms with COSE.  The details of the structure of
   COSE are defined in [I-D.ietf-cose-rfc8152bis-struct].

   This document along with [I-D.ietf-cose-rfc8152bis-struct] obsoletes
   RFC8152.

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-rfc8152bis>.  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 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

Schaad                 Expires September 12, 2019               [Page 1]
Internet-Draft               COSE Algorithms                  March 2019

   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 September 12, 2019.

Copyright Notice

   Copyright (c) 2019 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Terminology  . . . . . . . . . . . . . . . .   4
     1.2.  Changes from RFC8152  . . . . . . . . . . . . . . . . . .   4
     1.3.  Document Terminology  . . . . . . . . . . . . . . . . . .   4
     1.4.  CBOR Grammar  . . . . . . . . . . . . . . . . . . . . . .   4
     1.5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Signature Algorithms  . . . . . . . . . . . . . . . . . . . .   5
     2.1.  ECDSA . . . . . . . . . . . . . . . . . . . . . . . . . .   5
       2.1.1.  Security Considerations . . . . . . . . . . . . . . .   6
     2.2.  Edwards-Curve Digital Signature Algorithms (EdDSAs) . . .   7
       2.2.1.  Security Considerations . . . . . . . . . . . . . . .   8
   3.  Message Authentication Code (MAC) Algorithms  . . . . . . . .   8
     3.1.  Hash-Based Message Authentication Codes (HMACs) . . . . .   9
       3.1.1.  Security Considerations . . . . . . . . . . . . . . .  10
     3.2.  AES Message Authentication Code (AES-CBC-MAC) . . . . . .  10
       3.2.1.  Security Considerations . . . . . . . . . . . . . . .  11
   4.  Content Encryption Algorithms . . . . . . . . . . . . . . . .  12
     4.1.  AES GCM . . . . . . . . . . . . . . . . . . . . . . . . .  12
       4.1.1.  Security Considerations . . . . . . . . . . . . . . .  13
     4.2.  AES CCM . . . . . . . . . . . . . . . . . . . . . . . . .  13
       4.2.1.  Security Considerations . . . . . . . . . . . . . . .  16
     4.3.  ChaCha20 and Poly1305 . . . . . . . . . . . . . . . . . .  16
       4.3.1.  Security Considerations . . . . . . . . . . . . . . .  17
   5.  Key Derivation Functions (KDFs) . . . . . . . . . . . . . . .  17
     5.1.  HMAC-Based Extract-and-Expand Key Derivation Function
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