    Internet Engineering Task Force (IETF)                         S. Turner
    Request for Comments: 6161                                          IECA
    Updates: 6033                                                 April 2011
    Category: Standards Track
    ISSN: 2070-1721

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

    Abstract

       This document describes the conventions for using several Elliptic
       Curve cryptographic algorithms with the Cryptographic Message Syntax
       (CMS) encrypted key package 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 6033.

    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/rfc6161.

    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.

    Turner                       Standards Track                    [Page 1]

    RFC 6161      EC Algorithms for CMS Encrypted Key Packages    April 2011

    1.  Introduction

       This document describes the conventions for using Elliptic Curve
       cryptographic algorithms with the Cryptographic Message Syntax (CMS)
       encrypted key package content type [RFC6032].  Specifically, it
       includes conventions necessary to implement the following CMS content
       types: EnvelopedData [RFC5652] and SignedData [RFC5652].  This
       document amends [RFC6033].  Familiarity with [RFC6033] 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.  EnvelopedData

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

    3.  SignedData

       If an implementation encapsulates EncryptedKeyPackage with SignedData
       [RFC5652], then it MAY support the signature scheme ECDSA
       [RFC6090][RFC5753].

    4.  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.

    5.  Security Considerations

       The security considerations from [RFC5280], [RFC5480], [RFC5652],
       [RFC5753], [RFC6033], and [RFC6090] apply.

    6.  Normative References

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

    Turner                       Standards Track                    [Page 2]

    RFC 6161      EC Algorithms for CMS Encrypted Key Packages    April 2011

       [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.

       [RFC6032]  Turner, S. and R. Housley, "Cryptographic Message Syntax
                  (CMS) Encrypted Key Package Content Type", RFC 6032,
                  December 2010.

       [RFC6033]  Turner, S., "Algorithms for Cryptographic Message Syntax
                  (CMS) Encrypted Key Package Content Type", RFC 6033,
                  December 2010.

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

    Author's Address

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

       EMail: turners@ieca.com

    Turner                       Standards Track                    [Page 3]