IETF PKIX WG                                          Sean Turner,
Network Working Group                                          S. Turner
Request for Comments: 5546                                          IECA
Internet Draft                                   Daniel Brown, Certicom
Intended Status: Standard Track                   Kelvin Yiu, Microsoft
Updates: 4055 (once approved)              Russ Housley,                                                   D. Brown
Category: Standards Track                                       Certicom
                                                                  K. Yiu
                                                               Microsoft
                                                              R. Housley
                                                          Vigil Security
Expires: September 9, 2009                               Tim Polk,
                                                                 T. Polk
                                                                    NIST
                                                          March 9,
                                                                May 2009

                Update

       Updates for RSAES-OAEP and RSASSA-PSS Algorithm Parameters
                   draft-ietf-pkix-rfc4055-update-02.txt

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Abstract

   This document updates RFC 4055.  It updates the conventions for using
   the RSA Encryption Scheme - Optimal Asymmetric Encryption Padding
   (RSAES-OAEP) key transport algorithm in the Internet X.509 Public Key
   Infrastructure (PKI).  Specifically, it updates the conventions for
   algorithm parameters in an X.509 certificate's subjectPublicKeyInfo
   field.

Conventions used in this document

   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].

Discussion

   This draft is being discussed on the 'ietf-pkix' mailing list. To
   subscribe, send a message to ietf-pkix-request@imc.org with the
   single word subscribe in the body of the message. There is a Web site
   for the mailing list at <http://www.imc.org/ietf-pkix/>.

1.  Introduction

   RFC 4055 specifies conventions for using the RSA Encryption Scheme -
   Optimal Asymmetric Encryption Padding (RSAES-OAEP) key transport
   algorithm in the Internet X.509 Public Key Infrastructure (PKI).  It
   provides algorithm identifiers and parameters for RSAES-OAEP.

   This document updates the conventions for RSAES-OAEP parameters in
   the subjectPublicKeyInfo field of an X.509 certificate.  The PKIX WG
   Elliptic Curve Cryptography (ECC) design team recommended that Key
   Derivation Functions (KDFs) should not be constrained within a
   certificate; rather, KDF constraints should be negotiated in
   protocols that need to employ certificates.

   Only two paragraphs in [RFC4055] discuss RSAES-OAEP parameters in
   X.509 certificates: the second paragraph of section Section 4 and the first
   paragraph of section Section 4.1.  This document only updates these two
   paragraphs.  Section 3 updates the second paragraph in section Section 4 of
   [RFC4055], while section 3 Section 4 updates the second paragraph in section 4.1. Section
   4.1 of [RFC4055].  "Old:" prefaces the text to be replaced and "New:"
   prefaces the replacement text.

   This document also replaces incorrect references to the
   publicKeyAlgorithms field in Section 3 with references to the
   parameters field in the subjectPublicKeyInfo algorithm field. No
   other changes
   Section 3 also rewords the second and third paragraphs for clarity.

1.1.  Conventions Used in This Document

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

2.  Changes to Section 3 2nd (Second and 3rd Paragraph Third Paragraphs)

   This change clarifies the placement of RSASSA-PSS-params in the
   signature, signatureAlgorithm, and subjectPublicKeyInfo fields for CA
   certification authority (CA) and EE end-entity (EE) certificates.  It
   also clarifies the placement of RSASSA-PSS-
   params RSASSA-PSS-params in the
   signatureAlgorithm field in CRLs. certificate revocation lists (CRLs).

   Old:

   CAs that issue certificates with the id-RSASSA-PSS algorithm
   identifier SHOULD require the presence of parameters in the
   publicKeyAlgorithms field if the cA boolean flag is set in the basic
   constraints certificate extension.  CAs MAY require that the
   parameters be present in the publicKeyAlgorithms field for end-entity
   certificates.

   CAs that use the RSASSA-PSS algorithm for signing certificates SHOULD
   include RSASSA-PSS-params in the subjectPublicKeyInfo algorithm
   parameters in their own certificates.  CAs that use the RSASSA-PSS
   algorithm for signing certificates or CRLs MUST include RSASSA-PSS-
   params in the signatureAlgorithm parameters in the TBSCertificate or
   TBSCertList structures.

   New:

   When the id-RSASSA-PSS object identifier appears in the
   TBSCertificate or TBSCertList signature algorithm field, then the
   RSASSA-PSS-params structure MUST be included in the TBSCertificate or
   TBSCertList signature parameters field.

   When the id-RSASSA-PSS object identifier appears in the
   TBSCertificate subjectPublicKeyInfo algorithm field of CA
   certificates, then the parameters field SHOULD include the RSASSA-
   PSS-params structure.  When the id-RSASSA-PSS object identifier
   appears in the TBSCertificate subjectPublicKeyInfo algorithm field of
   EE certificates, then the parameters field MAY include the RSASSA-
   PSS-params structure.

   All certificates and CRLs signed by a CA that supports the id-RSASSA-
   PSS algorithm MUST include the RSASSA-PSS-params in the
   signatureAlgorithm parameters in Certificate and CertList structures,
   respectively.

3.  Changes to Section 4 2nd Paragraph (Second Paragraph)

   This change prohibits the inclusion of RSAES-OAEP-params in the
   subjectPublicKeyInfo field.  This was done because a) it does not
   affect interoperability and b) it aligns with PKIX practice to not
   include limitations on how the public key can be used in
   subjectPublicKeyInfo.  A poll of implementers was taken and there
   were no objections to this change as it did not affect current
   implmentations.
   implementations.

   Old:

   CAs that issue certificates with the id-RSAES-OAEP algorithm
   identifier SHOULD require the presence of parameters in the
   publicKeyAlgorithms field for all certificates.  Entities that use a
   certificate with a publicKeyAlgorithm value of id-RSA-OAEP where the
   parameters are absent SHOULD use the default set of parameters for
   RSAES-OAEP-params.  Entities that use a certificate with a
   publicKeyAlgorithm value of rsaEncryption SHOULD use the default set
   of parameters for RSAES-OAEP-params.

   New:

   CAs that issue certificates with the id-RSAES-OAEP algorithm
   identifier MUST NOT include parameters in the subjectPublicKeyInfo
   algorithm field.

4.  Changes to Section 4.1 1st Paragraph (First Paragraph)

   This change prohibits the inclusion of parameters in the
   subjectPublicKeyInfo field.  This was done because a) it does not
   affect interoperability and b) it aligns with PKIX practice to not
   include limitations on how the public key can be used in
   subjectPublicKeyInfo.  A poll of implementers was taken and there
   were no objections to this change as it did not affect current
   implmentations.
   implementations.

   Old:

   When id-RSAES-OAEP is used in an AlgorithmIdentifier, the parameters
   MUST employ the RSAES-OAEP-params syntax.  The parameters may be
   either absent or present when used as subject public key information.

   The parameters MUST be present when used in the algorithm identifier
   associated with an encrypted value.

   New:

   When id-RSAES-OAEP is used in an AlgorithmIdentifier, the parameters
   MUST employ the RSAES-OAEP-params syntax.  The parameters MUST be
   absent when used in the subjectPublicKeyInfo field.  The parameters
   MUST be present when used in the algorithm identifier associated with
   an encrypted value.

5.  Security Considerations

   The security considerations from [RFC4055] apply.

   If the RSAES-OAEP-params are negotiated, then the negotiation
   mechanism needs to provide integrity for these parameters.  For
   example, an S/MIME Agent can advertise their capabilities in the
   SMIMECapabilities attribute, which is either a signed attribute
   [RFC3851bis]
   [RFC3281bis] or a certificate extension [RFC4262].

6. IANA Considerations

   None

   {{Please remove this section prior to publication as an RFC.}}

7.  References

7.1.

6.1.  Normative References

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

   [RFC4055]     Schaad, J., Kaliski, B., and R. Housley, "Additional
                 Algorithms and Identifiers for RSA Cryptography for use
                 in the Internet X.509 Public Key Infrastructure
                 Certificate and Certificate Revocation List (CRL)
                 Profile", RFC 4055, June 2005.

7.2.

6.2.  Informative References

   [RFC4262]     S.     Santesson, S., "X.509 Certificate Extension for
                 Secure/Multipurpose Internet Mail Extensions (S/MIME)
                 Capabilities", RFC 4262, December 2005.

   [RFC3851bis]

   [RFC3281bis]  Turner, S., Farrell, S., and R. Housley, "An Internet
                 Attribute Certificate Profile for Authorization",
                 draft-ietf-pkix-3281update-04.txt, work-in-progress.

   /*** RFC EDITOR: Please replace RFC3851bis with RFCXYAZ when draft-
                 ietf-pkix-3281update is published.

Author's Work
                 in Progress, February 2009.

Authors' Addresses

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

   EMail: turners@ieca.com

   Kelvin Yiu
   Microsoft
   One Microsoft Way
   Redmond, WA 98052-6399
   USA

   Email:

   EMail: kelviny@microsoft.com

   Daniel R. L. Brown
   Certicom Corp
   5520 Explorer Drive #400
   Mississauga, ON L4W 5L1
   CANADA

   EMail: dbrown@certicom.com

   Russ Housley
   Vigil Security, LLC
   918 Spring Knoll Drive
   Herndon, VA 20170
   USA

   EMail: housley@vigilsec.com

   Tim Polk
   NIST
   Building 820, Room 426
   Gaithersburg, MD 20899
   USA

   EMail: wpolk@nist.gov