Internet Engineering Task Force (IETF)                         S. Turner
Request for Comments: 6162                                          IECA
Updates: 5959                                                 April 2011
Category: Standards Track
ISSN: 2070-1721


    Elliptic Curve Algorithms for Cryptographic Message Syntax (CMS)
                  Asymmetric Key Package Content Type

Abstract

   This document describes conventions for using Elliptic Curve
   cryptographic algorithms with SignedData and EnvelopedData to protect
   the AsymmetricKeyPackage content type.  Specifically, it includes
   conventions necessary to implement Elliptic Curve Diffie-Hellman
   (ECDH) with EnvelopedData and Elliptic Curve Digital Signature
   Algorithm (ECDSA) with SignedData.  This document extends RFC 5959.

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 5741.

   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/rfc6162.

Copyright Notice

   Copyright (c) 2011 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.

1.  Introduction

   [RFC5959] describes conventions necessary to protect the
   AsymmetricKeyPackage content type [RFC5958] with Cryptographic
   Message Syntax (CMS) protecting the following content types:
   SignedData [RFC5652], EnvelopedData [RFC5652], EncryptedData
   [RFC5652], AuthenticatedData [RFC5652], and AuthEnvelopedData
   [RFC5083].  This document amends [RFC5959] by extending the
   algorithms used with SignedData and EnvelopedData to include Elliptic
   Curve Digital Signature Algorithm (ECDSA) and Elliptic Curve Diffie-
   Hellman (ECDH), respectively.  Familiarity with [RFC5959] and
   [RFC5753] is assumed.

   This document does not define any new algorithms; instead, it refers
   to previously defined algorithms.

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

2.  AsymmetricKeyPackage

   As noted in Asymmetric Key Packages [RFC5958], CMS can be used to
   protect the AsymmetricKeyPackage.  The following provides guidance
   for SignedData [RFC5652] and EnvelopedData [RFC5652] when used with
   Elliptic Curve algorithms.

2.1.  SignedData

   If an implementation supports SignedData, then it MAY support ECDSA
   [RFC6090][RFC5753].

2.2.  EnvelopedData

   When key agreement is used, standard (as opposed to cofactor) ECDH
   [RFC6090][RFC5753] MAY be supported.

3.  Public Key Sizes

   The easiest way to implement SignedData and EnvelopedData is with
   public key certificates [RFC5280][RFC5480].  If an implementation
   supports ECDSA or ECDH, then it MUST support keys on the P-256 curve.

4.  Security Considerations

   The security considerations from [RFC5280], [RFC5480], [RFC5652],
   [RFC5753], [RFC5959], and [RFC6090] apply.

5.  References

5.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC5480]  Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
              "Elliptic Curve Cryptography Subject Public Key
              Information", RFC 5480, March 2009.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, September 2009.

   [RFC5753]  Turner, S. and D. Brown, "Use of Elliptic Curve
              Cryptography (ECC) Algorithms in Cryptographic Message
              Syntax (CMS)", RFC 5753, January 2010.

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958, August
              2010.

   [RFC5959]  Turner, S., "Algorithms for Asymmetric Key Package Content
              Type", RFC 5959, August 2010.

   [RFC6090]  McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic
              Curve Cryptography Algorithms", RFC 6090, February 2011.

5.2.  Informative Reference

   [RFC5083]  Housley, R., "Cryptographic Message Syntax (CMS)
              Authenticated-Enveloped-Data Content Type", RFC 5083,
              November 2007.

Author's Address

   Sean Turner
   IECA, Inc.
   3057 Nutley Street, Suite 106
   Fairfax, VA 22031
   USA

   EMail: turners@ieca.com