Cryptographic Message Syntax (CMS) Encrypted Key Package Content Type
RFC 6032

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Internet Engineering Task Force (IETF)                         S. Turner
Request for Comments: 6032                                          IECA
Category: Standards Track                                     R. Housley
ISSN: 2070-1721                                           Vigil Security
                                                           December 2010

                   Cryptographic Message Syntax (CMS)
                   Encrypted Key Package Content Type

Abstract

   This document defines the Cryptographic Message Syntax (CMS)
   encrypted key package content type, which can be used to encrypt a
   content that includes a key package, such as a symmetric key package
   or an asymmetric key package.  It is transport independent.  CMS can
   be used to digitally sign, digest, authenticate, or further encrypt
   this content type.  It is designed to be used with the CMS Content
   Constraints (CCC) extension, which does not constrain the
   EncryptedData, EnvelopedData, and AuthEnvelopedData.

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/rfc6032.

Turner & Housley             Standards Track                    [Page 1]
RFC 6032         CMS Encrypted Key Package Content Type    December 2010

Copyright Notice

   Copyright (c) 2010 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

   The Cryptographic Message Syntax (CMS) specification [RFC5652]
   defines mechanisms to digitally sign, digest, authenticate, or
   encrypt arbitrary message content.  Many specifications define
   content types intended for use with CMS.  [RFC6031] and [RFC5958]
   define symmetric key package and asymmetric key package content types
   that can be signed or encrypted using CMS.  CMS allows the
   composition of complex messages with an arbitrary number of layers.
   CMS has been augmented by several specifications ([RFC3274],
   [RFC4073], and [RFC5083]) that define additional mechanisms to enable
   creation of messages of arbitrary depth and breadth using a variety
   of authentication, encryption, and compression techniques.

   The CMS Content Constraints (CCC) certificate extension [RFC6010]
   defines an authorization mechanism that allows recipients to
   determine whether the originator of an authenticated CMS content type
   is authorized to produce messages of that type.  CCC is used to
   authorize CMS-protected content.  CCC cannot be used to constrain the
   following structures that are used to provide layers of protection:
   SignedData, EnvelopedData, EncryptedData, DigestData, CompressedData,
   AuthenticatedData, ContentCollection, ContentWithAttributes, or
   AuthEnvelopedData.

   Using the existing CMS mechanisms, producers of authenticated
   plaintext key packages can be authorized by including a CCC extension
   containing the appropriate content type in the producer's
   certificate.  However, these mechanisms cannot be used to authorize
   the producers of encrypted key material.  In some key management
   systems, encrypted key packages are exchanged between entities that
   cannot decrypt the key package.  The encrypted key package itself may

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RFC 6032         CMS Encrypted Key Package Content Type    December 2010

   be authenticated and passed to another entity.  In these cases,
   checking the authorization of the producer of the encrypted key
   package may be desired at the intermediate points.

   This document defines the encrypted key package content type, which
   can be used to encrypt a content that includes a key package, such as
   a symmetric key package [RFC6031] or an asymmetric key package
   [RFC5958].  It is transport independent.  The Cryptographic Message
   Syntax (CMS) [RFC5652] can be used to digitally sign, digest,
   authenticate, or further encrypt this content type.