[Docs] [txt|pdf] [Tracker] [Email] [Nits]

Versions: 00 01 02 03 04 05 RFC 5958

Network Working Group                                 Sean Turner, IECA
Internet Draft                                          20 October 2008
Intended Status: Standard Track
Obsoletes: RFC 5208 (once approved)
Expires: 20 April 2009



                          Asymmetric Key Packages
                  draft-turner-asymmetrickeyformat-00.txt


Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on 20 April 2009.

Copyright Notice

   Copyright (C) The IETF Trust (2008).

Abstract

   This document defines the syntax for private key information and a
   content type for it.  Private-key information includes a private key
   for some public-key algorithm and a set of attributes.  The document
   also describes a syntax for encrypted private keys.  The
   Cryptographic Message Syntax, as defined in RFC 3852, can be used to




Turner                  Expires 20 April 2009                  [Page 1]

Internet-Draft         Asymmetric Key Packages             October 2008


   digitally sign, digest, authenticate, or encrypt the asymmetric key
   format content type.  This document obsoletes RFC 5208.

Table of Contents

   1. Introduction...................................................2
      1.1. Requirements Terminology..................................2
      1.2. ASN.1 Syntax Notation.....................................2
      1.3. Changes since RFC 5208....................................2
   2. Asymmetric Key Package Content Type............................3
   3. Encrypted Private Key Info.....................................4
   4. Protecting the AsymmetricKeyPackage............................5
   5. Other Considerations...........................................5
   6. Security Considerations........................................6
   7. IANA Considerations............................................6
   8. References.....................................................6
      8.1. Normative References......................................6
      8.2. Non-Normative References..................................7
   APPENDIX A: ASN.1 Module..........................................8

1. Introduction

   This document defines the syntax for private key information and a
   content type for it.  Private-key information includes a private key
   for some public-key algorithm and a set of attributes.  The document
   also describes a syntax for encrypted private keys.  The
   Cryptographic Message Syntax [RFC3852] can be used to digitally sign,
   digest, authenticate, or encrypt the asymmetric key format content
   type.  This document obsoletes [RFC5208].

1.1. Requirements 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].

1.2. ASN.1 Syntax Notation

   The key package is defined using ASN.1 [X.680], [X.681], [X.682], and
   [X.683].

1.3. Changes since RFC 5208

   The following are the changes since [RFC5208]:

   - Defined Asymmetric Key Package CMS content type.

   - Removed IMPLICIT from aKeyAttrs to align text with module.



Turner                  Expires 20 April 2009                  [Page 2]

Internet-Draft         Asymmetric Key Packages             October 2008


   - Added public key to OneAsymmetricKey and added new version number.

   - Added that PKCS#9 attributes MAY be supported.

   - Added Other Considerations section.

2. Asymmetric Key Package Content Type

   The asymmetric key package content type is used to transfer one or
   more plaintext asymmetric keys from one party to another.  An
   asymmetric key package MAY be encapsulated in one or more CMS
   protecting content types (see Section 4).  This content type MUST be
   DER encoded [X.690].

   The asymmetric key package content type has the following syntax:

     PKCS7-CONTENT-TYPE ::= TYPE-IDENTIFIER

     asymmetric-key-package PKCS7-CONTENT-TYPE ::=
       { AsymmetricKeyPackage IDENTIFIED BY id-ct-KP-aKeyPackage }

     id-ct-KP-aKeyPackage OBJECT IDENTIFIER ::= |
       { TBD }

     AsymmetricKeyPackage ::= SEQUENCE SIZE (1..MAX) OF OneAsymmetricKey

     OneAsymmetricKey ::= SEQUENCE {
       version              Version,
       privateKeyAlgorithm  PrivateKeyAlgorithmIdentifier,
       privateKey           PrivateKey, -- DER encoded
       aKeyAttrs        [0] Attributes OPTIONAL,
       publicKey        [1] PublicKey OPTIONAL }

     PrivateKeyInfo ::= OneAsymmetricKey -- Used in [P12]

     Version ::= INTEGER { v1(0), v2(1) } (v1, v2,...)

     PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier
                                        { { PrivateKeyAlgorithms } }

     PrivateKey ::= OCTET STRING
                        -- Content varies based on type of key. The
                        -- algorithm identifier dictates the format of
                        -- the key. DSA is INTEGER, ECDSA is INTEGER

     PublicKey ::= OCTET STRING
                       -- Content varies based on type of key. The
                       -- algorithm identifier dictates the format of
                       -- the key. DSA is INTEGER, ECDSA is OCTET STRING


Turner                  Expires 20 April 2009                  [Page 3]

Internet-Draft         Asymmetric Key Packages             October 2008


     Attributes ::= Set of Attribute

   The AsymmetricKeyPackage contains one or more OneAsymmetricKey
   elements.  The syntax accommodates keying material attributes (e.g.,
   certificates), a private key, an optional public key and optional
   asymmetric algorithm parameters.  In general, either the public key
   or the certificate will be present.  In very rare cases will both the
   public key and the certificate be present as this includes two copies
   of the public key.  The fields in OneAsymmetricKey are used as
   follows:

   - version identifies version of the asymmetric key package content
     structure.  For this version of the specification, version MUST be
     v1 if the publicKey field is absent and it MUST be set to v2 if the
     publicKey field is present.

   - privateKeyAlgorithm identifies the private key algorithm and
     optionally contains parameters associated with the asymmetric key.
     The algorithm is identified by an OID and the parameters format
     depends on the OID.  The value placed in
     privateKeyAlgorithmIdentifier is the value an originator would
     apply to indicate which algorithm was used.

   - privateKey is an OCTET STRING whose contents are the DER encoded
     private key.  The interpretation of the contents is defined in the
     registration of the private-key algorithm.

   - attributes is optional.  It contains information corresponding to
     the public key (e.g., certificates).  The attributes field uses the
     class ATTRIBUTE which is restricted by the SupportedAttributes
     parameterized type.  SupportedAttributes is an open ended set in
     this document.  Others documents can constrain these values.
     Attributes from [RFC2985] MAY be supported.

   - publicKey is optional.  When present, it contains the public key
     encoded as an OCTET STRING.  The structure within the octet string,
     if any, depends on the privateKeyAlgorithm.

3. Encrypted Private Key Info

   This section gives the syntax for encrypted private-key information,
   which is used with the [P12].

   Encrypted private-key information shall have ASN.1 type
   EncryptedPrivateKeyInfo:

     EncryptedPrivateKeyInfo ::= SEQUENCE {
       encryptionAlgorithm  EncryptionAlgorithmIdentifier,
       encryptedData        EncryptedData }


Turner                  Expires 20 April 2009                  [Page 4]

Internet-Draft         Asymmetric Key Packages             October 2008


     EncryptionAlgorithmIdentifier ::= AlgorithmIdentifier
                                        { { KeyEncryptionAlgorithms } }

     EncryptedData ::= OCTET STRING

   The EncAsymmetricKeyPackage contains one or more
   EncryptedPrivateKeyInfo elements.  The fields in
   EncryptedPrivateKeyInfo are used as follows:

   - encryptionAlgorithm identifies the algorithm under which the
     private-key information is encrypted.  Implementations MUST the TBD
     algorithm.

   - encryptedData is the result of encrypting the private-key
     information  (i.e., the PrivateKeyInfo).

   The encryption process involves the following two steps:

   1. The private-key information is BER encoded, yielding an octet
      string.

   2. The result of step 1 is encrypted with the secret key to give an
      octet string, the result of the encryption process.

4. Protecting the AsymmetricKeyPackage

   CMS [RFC3852] protecting content types can be used to provide
   security to the AsymmetricKeyPackage:

   - SignedData can be used to apply a digital signature to the
     AsymmetricKeyPackage.

   - EncryptedData can be used to encrypt the AsymmetricKeyPackage
     encapsulate the AsymmetricKeyPackage to provide confidentiality but
     does not distribute the content encryption keys.

   - EnvelopedData can be used to encrypt the AsymmetricKeyPackage with
     simple symmetric encryption, where the sender and the receiver
     already share the necessary encryption key

   - AuthenticatedData can be used to protect the AsymmetricKeyPackage
     with message authentication codes, where key management information
     is handled in a manner similar to EnvelopedData.

5. Other Considerations

   This document defines the syntax and the semantics for content types
   that exchange asymmetric keys.  There are two other standards for
   transporting asymmetric private keys:


Turner                  Expires 20 April 2009                  [Page 5]

Internet-Draft         Asymmetric Key Packages             October 2008


   - Personal Information Exchange (PFX) or more commonly referred to as
     P12 [P12], is a transfer syntax for personal identity information,
     including private keys, certificates, miscellaneous secrets, and
     extensions.  Both PrivateKeyInfo and EncryptedPrivateKeyInfo can be
     carried in a P12 message.

   - Microsoft's Exchange Security format, which is a proprietary
     format.

   When locally storing private keys, the file format is either a DER
   encoded file with the file extension .p12 or a PEM encoded file with
   the file extension .pem.

   When the private key is a character string, the OCTET STRING contains
   an embedded UTF8String.

6. Security Considerations

   Protection of the private-key information is vital to public-key
   cryptography.  Disclosure of the private-key material to another
   entity can lead to masquerades.  The encryption algorithm used in the
   encryption process must be as 'strong' as the key it is protecting.

   The asymmetric key package contents are not protected.  This content
   type can be combined with a security protocol to protect the contents
   of the package.

   The encrypted asymmetric key package contents are protected; as noted
   above the encryption algorithm must be as 'strong' as the key it is
   protecting.

7. IANA Considerations

   None: All identifiers are already registered.  Please remove this
   section prior to publication as an RFC.

8. References

8.1. Normative References

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

   [RFC3852] Housley, R., "Cryptographic Message Syntax (CMS)", RFC3852,
   July 2004.

   [X.680] ITU-T Recommendation X.680 (2002) | ISO/IEC 8824-1:2002.
   Information Technology - Abstract Syntax Notation One.



Turner                  Expires 20 April 2009                  [Page 6]

Internet-Draft         Asymmetric Key Packages             October 2008


   [X.681] ITU-T Recommendation X.681 (2002) | ISO/IEC 8824-2:2002.
   Information Technology - Abstract Syntax Notation One: Information
   Object Specification.

   [X.682] ITU-T Recommendation X.682 (2002) | ISO/IEC 8824-3:2002.
   Information Technology - Abstract Syntax Notation One: Constraint
   Specification.

   [X.683] ITU-T Recommendation X.683 (2002) | ISO/IEC 8824-4:2002.
   Information Technology - Abstract Syntax Notation One:
   Parameterization of ASN.1 Specifications.

   [X.690] ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002.
   Information Technology - ASN.1 encoding rules: Specification of Basic
   Encoding Rules (BER), Canonical Encoding Rules (CER) and
   Distinguished Encoding Rules (DER).

8.2. Non-Normative References

   [P12] RSA Laboratories, "PKCS #12 v1.0: Personal Information Exchange
   Syntax", June 1999.

   [RFC2985] Nystrom, M., and B. Kaliski, "PKCS #9: Selected Object
   Classes and Attribute Types Version 2.0", RFC 2985, November 2000.

   [RFC5208] Kaliski, B., "PKCS #8: Private Key Information Syntax
   Standard Version 1.2", RFC 5208, May 2008.
























Turner                  Expires 20 April 2009                  [Page 7]

Internet-Draft         Asymmetric Key Packages             October 2008


APPENDIX A: ASN.1 Module

   This annex provides the normative ASN.1 definitions for the
   structures described in this specification using ASN.1 as defined in
   [X.680] through [X.683].

   AsymmetricKeyPackageModulev1  { tbd }

   DEFINITIONS IMPLICIT TAGS ::=

   BEGIN

   -- EXPORTS ALL

   IMPORTS NOTHING

   Attribute{}, ATTRIBUTE, AlgorithmIdentifier{}
     FROM PKIX-CommonTypes
       { iso(1) identified-organization(3) dod(6) internet(1)
         security(5) mechanisms(5) pkix(7) id-mod(0)
         id-mod-pkixCommon(43) }

     id-aes128-wrap, id-aes192-wrap, id-aes1256-wrap
      FROM CMSAesRsaesOaep
        { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
          pkcs-9(9) smime(16) modules(0) id-mod-cms-aes(19) }

   ;

   PKCS7-CONTENT-TYPE ::= TYPE-IDENTIFIER

   KeyPackageContentTypes PKCS7-CONTENT-TYPE ::= {
     asymmetric-key-package |
     ... -- Expect additional content types --
   }

   asymmetric-key-package PKCS7-CONTENT-TYPE ::=
     { AsymmetricKeyPackage IDENTIFIED BY id-ct-KP-aKeyPackage }

   id-ct-KP-aKeyPackage OBJECT IDENTIFIER ::=
     { TBD }

   AsymmetricKeyPackage ::= SEQUENCE SIZE (1..MAX) OF OneAsymmetricKey








Turner                  Expires 20 April 2009                  [Page 8]

Internet-Draft         Asymmetric Key Packages             October 2008


   OneAsymmetricKey ::= SEQUENCE {
     version              Version,
     privateKeyAlgorithm  PrivateKeyAlgorithmIdentifier,
     privateKey           PrivateKey, -- DER encoded
     aKeyAttrs        [0] Attributes OPTIONAL,
     publicKey        [1] PublicKey OPTIONAL }

   PrivateKeyInfo ::= OneAsymmetricKey

   Version ::= INTEGER {v1(0), v2(1)} (v1, v2,...)

   PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier
                                      { { PrivateKeyAlgorithms } }

   PrivateKey ::= OCTET STRING -- Content varies based on type of key
                               -- DSA is INTEGER, ECDSA is ECPublicKey

   PublicKey ::= OCTET STRING

   Attributes ::= Set of Attribute { { SupportAttributes } }

   SupportedAttributes ATTRIBUTE :: {
     ... -- For local profiles
   }

   EncAsymmetricKeyPackage ::= SEQUENCE SIZE (1..MAX) OF
                                EncryptedPrivateKeyInfo

   EncryptedPrivateKeyInfo ::= SEQUENCE {
     encryptionAlgorithm  EncryptionAlgorithmIdentifier,
     encryptedData        EncryptedData }

   EncryptionAlgorithmIdentifier ::= AlgorithmIdentifier
                                       { { KeyEncryptionAlgorithms } }

   EncryptedData ::= OCTET STRING -- Encrypted PrivateKeyInfo

   PrivateKeyAlgorithms ALGORITHM-IDENTIFIER ::= {
     ... -- Extensible
   }

   KeyEncryptionAlgorithms ALGORITHM-IDENTIFIER ::= {
     id-aes128-wrap |
     id-aes192-wrap |
     id-aes256-wrap,
     ... -- Extensible
   }

   END


Turner                  Expires 20 April 2009                  [Page 9]

Internet-Draft         Asymmetric Key Packages             October 2008


Acknowledgements

   Many thanks go out to the Burt Kaliski and Jim Randall at RSA.
   Without the prior version of the document, this one wouldn't exist.

   We'd also like to thank Pasi Eronen and Russ Housley.

Author's Address

   Sean Turner

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

   Email: turners@ieca.com


































Turner                  Expires 20 April 2009                 [Page 10]

Internet-Draft         Asymmetric Key Packages             October 2008


Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at ietf-
   ipr@ietf.org.

Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).







Turner                  Expires 20 April 2009                 [Page 11]

Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/