IETF PKIX WG Sean Turner, IECA
Internet Draft Daniel Brown, Certicom
Intended Status: Standard Track Kelvin Yiu, Microsoft
Updates: 4055 (once approved) Russ Housley, Vigil Security
Expires: September 9, 2009 Tim Polk, NIST
March 9, 2009
Update for RSAES-OAEP 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 4 and the first
paragraph of section 4.1. This document only updates these two
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paragraphs. Section 3 updates the second paragraph in section 4
while section 3 updates the second paragraph in section 4.1. "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 are made to the RSASSA-PSS sections.
2. Changes to Section 3 2nd and 3rd Paragraph
This change clarifies the placement of RSASSA-PSS-params in the
signature, signatureAlgorithm, and subjectPublicKeyInfo fields for CA
and EE certificates. It also clarifies the placement of RSASSA-PSS-
params in the signatureAlgorithm field in 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.
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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
This change prohibits the inclusion of RSAES-OAEP-params in the
subjectPublicKeyInfo field. This was done because a) it does not
affect interoperability b) 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.
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
This change prohibits the inclusion of parameters in the
subjectPublicKeyInfo field. This was done because a) it does not
affect interoperability b) 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.
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.
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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 signed attribute
[RFC3851bis] or a certificate extension [RFC4262].
6. IANA Considerations
None
{{Please remove this section prior to publication as an RFC.}}
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, 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.
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7.2. Informative References
[RFC4262] S. Santesson, "X.509 Certificate Extension for
Secure/Multipurpose Internet Mail Extensions (S/MIME)
Capabilities", RFC 4262, December 2005.
[RFC3851bis] 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.
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Author's 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: 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
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