Algorithms for Asymmetric Key Package Content Type
RFC 5959

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Internet Engineering Task Force (IETF)                         S. Turner
Request for Comments: 5959                                          IECA
Category: Standards Track                                    August 2010
ISSN: 2070-1721

           Algorithms for Asymmetric Key Package Content Type

Abstract

   This document describes the conventions for using several
   cryptographic algorithms with the EncryptedPrivateKeyInfo structure,
   as defined in RFC 5958.  It also includes conventions necessary to
   protect the AsymmetricKeyPackage content type with SignedData,
   EnvelopedData, EncryptedData, AuthenticatedData, 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/rfc5959.

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.

Turner                       Standards Track                    [Page 1]
RFC 5959         Algorithms for Asymmetric Key Packages      August 2010

1.  Introduction

   This document describes the conventions for using several
   cryptographic algorithms with the EncryptedPrivateKeyInfo structure
   [RFC5958].  The EncryptedPrivateKeyInfo is used by [P12] to encrypt
   PrivateKeyInfo [RFC5958].  It is similar to EncryptedData [RFC5652]
   in that it has no recipients, no originators, and no content
   encryption keys and requires keys to be managed by other means.

   This document also includes conventions necessary to protect the
   AsymmetricKeyPackage content type [RFC5958] with Cryptographic
   Message Syntax (CMS) protecting content types: SignedData [RFC5652],
   EnvelopedData [RFC5652], EncryptedData [RFC5652], AuthenticatedData
   [RFC5652], and AuthEnvelopedData [RFC5083].  Implementations of
   AsymmetricKeyPackage do not require support for any CMS protecting
   content type; however, if the AsymmetricKeyPackage is CMS protected
   it is RECOMMENDED that conventions defined herein be followed.

   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", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  EncryptedPrivateKeyInfo

   The de facto standard used to encrypt the PrivateKeyInfo structure,
   which is subsequently placed in the EncryptedPrivateKeyInfo
   encryptedData field, is Password Based Encryption (PBE) based on PKCS
   #5 [RFC2898] and PKCS #12 [P12].  The major difference between PKCS
   #5 and PKCS #12 is the supported encoding for the password: ASCII for
   PKCS #5 and Unicode for PKCS #12, encoded as specified in Section B.1
   of [P12].  [RFC2898] specifies two PBE Schemes (PBES) 1 and 2;
   [RFC2898] recommends PBES2 for new specification.  PBES2 with a key
   derivation algorithm of PBKDF2 using HMAC with SHA-256 [RFC5754] and
   an encryption algorithm of AES Key Wrap with Padding as defined in
   [RFC5649] MUST be supported.  AES-256 Key Wrap with Padding [RFC5649]
   MAY also be supported as an encryption algorithm.

3.  AsymmetricKeyPackage

   As noted in Asymmetric Key Packages [RFC5958], CMS can be used to
   protect the AsymmetricKeyPackage.  The following provides guidance
   for SignedData [RFC5652], EnvelopedData [RFC5652], EncryptedData

Turner                       Standards Track                    [Page 2]
RFC 5959         Algorithms for Asymmetric Key Packages      August 2010

   [RFC5652], AuthenticatedData [RFC5652], and AuthEnvelopedData
   [RFC5083].

3.1.  SignedData

   If an implementation supports SignedData, then it MUST support the
   signature scheme RSA [RFC3370] [RFC5754] and SHOULD support the
   signature schemes RSASSA-PSS [RFC4056] and DSA [RFC3370] [RFC5754].
   Additionally, implementations MUST support in concert with these