Network Working Group K. Zeilenga Request for Comments: 4523 OpenLDAP Foundation Obsoletes: 2252, 2256, 2587 June 2006 Category: Standards Track
Lightweight Directory Access Protocol (LDAP) Schema Definitions for X.509 Certificates
Status of This Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document describes schema for representing X.509 certificates, X.521 security information, and related elements in directories accessible using the Lightweight Directory Access Protocol (LDAP). The LDAP definitions for these X.509 and X.521 schema elements replace those provided in RFCs 2252 and 2256.
This document provides LDAP [RFC4510] schema definitions [RFC4512] for a subset of elements specified in X.509 [X.509] and X.521 [X.521], including attribute types for certificates, cross certificate pairs, and certificate revocation lists; matching rules to be used with these attribute types; and related object classes. LDAP syntax definitions are also provided for associated assertion and attribute values.
As the semantics of these elements are as defined in X.509 and X.521, knowledge of X.509 and X.521 is necessary to make use of the LDAP schema definitions provided herein.
This document, together with [RFC4510], obsoletes RFCs 2252 and 2256 in their entirety. The changes (in this document) made since RFC 2252 and RFC 2256 include:
- addition of pkiUser, pkiCA, and deltaCRL classes;
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RFC 4523 LDAP X.509 Schema June 2006
- update of attribute types to include equality matching rules in accordance with their X.500 specifications;
- addition of certificate, certificate pair, certificate list, and algorithm identifier matching rules; and
- addition of LDAP syntax for assertion syntaxes for these matching rules.
This document obsoletes RFC 2587. The X.509 schema descriptions for LDAPv2 [RFC1777] are Historic, as is LDAPv2 [RFC3494].
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 BCP 14 [RFC2119].
Schema definitions are provided using LDAP description formats [RFC4512]. Definitions provided here are formatted (line wrapped) for readability.
A value of this syntax is an X.509 Certificate [X.509, clause 7].
Due to changes made to the definition of a Certificate through time, no LDAP-specific encoding is defined for this syntax. Values of this syntax SHOULD be encoded using Distinguished Encoding Rules (DER) [X.690] and MUST only be transferred using the ;binary transfer option [RFC4522]; that is, by requesting and returning values using attribute descriptions such as "userCertificate;binary".
As values of this syntax contain digitally signed data, values of this syntax and the form of each value MUST be preserved as presented.
A value of this syntax is an X.509 CertificateList [X.509, clause 7.3].
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Due to changes made to the definition of a CertificateList through time, no LDAP-specific encoding is defined for this syntax. Values of this syntax SHOULD be encoded using DER [X.690] and MUST only be transferred using the ;binary transfer option [RFC4522]; that is, by requesting and returning values using attribute descriptions such as "certificateRevocationList;binary".
As values of this syntax contain digitally signed data, values of this syntax and the form of each value MUST be preserved as presented.
A value of this syntax is an X.509 CertificatePair [X.509, clause 11.2.3].
Due to changes made to the definition of an X.509 CertificatePair through time, no LDAP-specific encoding is defined for this syntax. Values of this syntax SHOULD be encoded using DER [X.690] and MUST only be transferred using the ;binary transfer option [RFC4522]; that is, by requesting and returning values using attribute descriptions such as "crossCertificatePair;binary".
As values of this syntax contain digitally signed data, values of this syntax and the form of each value MUST be preserved as presented.
A value of this syntax is an X.509 SupportedAlgorithm [X.509, clause 11.2.7].
Due to changes made to the definition of an X.509 SupportedAlgorithm through time, no LDAP-specific encoding is defined for this syntax. Values of this syntax SHOULD be encoded using DER [X.690] and MUST only be transferred using the ;binary transfer option [RFC4522]; that is, by requesting and returning values using attribute descriptions such as "supportedAlgorithms;binary".
As values of this syntax contain digitally signed data, values of this syntax and the form of the value MUST be preserved as presented.
A value of this syntax is an X.509 CertificateExactAssertion [X.509, clause 11.3.1]. Values of this syntax MUST be encoded using the Generic String Encoding Rules (GSER) [RFC3641]. Appendix A.1 provides an equivalent Augmented Backus-Naur Form (ABNF) [RFC4234] grammar for this syntax.
A value of this syntax is an X.509 CertificateAssertion [X.509, clause 11.3.2]. Values of this syntax MUST be encoded using GSER [RFC3641]. Appendix A.2 provides an equivalent ABNF [RFC4234] grammar for this syntax.
A value of this syntax is an X.509 CertificatePairExactAssertion [X.509, clause 11.3.3]. Values of this syntax MUST be encoded using GSER [RFC3641]. Appendix A.3 provides an equivalent ABNF [RFC4234] grammar for this syntax.
A value of this syntax is an X.509 CertificatePairAssertion [X.509, clause 11.3.4]. Values of this syntax MUST be encoded using GSER [RFC3641]. Appendix A.4 provides an equivalent ABNF [RFC4234] grammar for this syntax.
( 1.3.6.1.1.15.5 DESC 'X.509 Certificate List Exact Assertion' )
A value of this syntax is an X.509 CertificateListExactAssertion [X.509, clause 11.3.5]. Values of this syntax MUST be encoded using GSER [RFC3641]. Appendix A.5 provides an equivalent ABNF grammar for this syntax.
( 1.3.6.1.1.15.6 DESC 'X.509 Certificate List Assertion' )
A value of this syntax is an X.509 CertificateListAssertion [X.509, clause 11.3.6]. Values of this syntax MUST be encoded using GSER [RFC3641]. Appendix A.6 provides an equivalent ABNF [RFC4234] grammar for this syntax.
This section introduces a set of certificate and related matching rules for use in LDAP. These rules are intended to act in accordance with their X.500 counterparts.
The certificateExactMatch matching rule compares the presented certificate exact assertion value with an attribute value of the certificate syntax as described in clause 11.3.1 of [X.509].
The certificateMatch matching rule compares the presented certificate assertion value with an attribute value of the certificate syntax as described in clause 11.3.2 of [X.509].
The certificatePairExactMatch matching rule compares the presented certificate pair exact assertion value with an attribute value of the certificate pair syntax as described in clause 11.3.3 of [X.509].
The certificatePairMatch matching rule compares the presented certificate pair assertion value with an attribute value of the certificate pair syntax as described in clause 11.3.4 of [X.509].
The certificateListExactMatch matching rule compares the presented certificate list exact assertion value with an attribute value of the certificate pair syntax as described in clause 11.3.5 of [X.509].
( 2.5.13.38 NAME 'certificateListExactMatch' DESC 'X.509 Certificate List Exact Match' SYNTAX 1.3.6.1.1.15.5 )
The certificateListMatch matching rule compares the presented certificate list assertion value with an attribute value of the certificate pair syntax as described in clause 11.3.6 of [X.509].
( 2.5.13.39 NAME 'certificateListMatch' DESC 'X.509 Certificate List Match' SYNTAX 1.3.6.1.1.15.6 )
The algorithmIdentifierMatch mating rule compares a presented algorithm identifier with an attribute value of the supported algorithm as described in clause 11.3.7 of [X.509].
The userCertificate attribute holds the X.509 certificates issued to the user by one or more certificate authorities, as discussed in clause 11.2.1 of [X.509].
( 2.5.4.36 NAME 'userCertificate' DESC 'X.509 user certificate' EQUALITY certificateExactMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.8 )
As required by this attribute type's syntax, values of this attribute are requested and transferred using the attribute description "userCertificate;binary".
The cACertificate attribute holds the X.509 certificates issued to the certificate authority (CA), as discussed in clause 11.2.2 of [X.509].
( 2.5.4.37 NAME 'cACertificate' DESC 'X.509 CA certificate' EQUALITY certificateExactMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.8 )
As required by this attribute type's syntax, values of this attribute are requested and transferred using the attribute description "cACertificate;binary".
As required by this attribute type's syntax, values of this attribute are requested and transferred using the attribute description "crossCertificatePair;binary".
As required by this attribute type's syntax, values of this attribute are requested and transferred using the attribute description "certificateRevocationList;binary".
As required by this attribute type's syntax, values of this attribute are requested and transferred using the attribute description "authorityRevocationList;binary".
As required by this attribute type's syntax, values of this attribute MUST be requested and transferred using the attribute description "deltaRevocationList;binary".
As required by this attribute type's syntax, values of this attribute MUST be requested and transferred using the attribute description "supportedAlgorithms;binary".
This class is used to represent objects that act as CRL distribution points, as discussed in clause 11.1.3 of [X.509].
( 2.5.6.19 NAME 'cRLDistributionPoint' DESC 'X.509 CRL distribution point' SUP top STRUCTURAL MUST cn MAY ( certificateRevocationList $ authorityRevocationList $ deltaRevocationList ) )
This object class is used to augment entries for objects participating in certificate-based authentication, as defined in clause 6.15 of [X.521]. This object class is deprecated in favor of pkiUser.
( 2.5.6.15 NAME 'strongAuthenticationUser' DESC 'X.521 strong authentication user' SUP top AUXILIARY MUST userCertificate )
This object class is used to augment entries for objects that act as certificate authorities, as defined in clause 6.17 of [X.521]. This object class is deprecated in favor of pkiCA.
( 2.5.6.16 NAME 'certificationAuthority' DESC 'X.509 certificate authority' SUP top AUXILIARY MUST ( authorityRevocationList $ certificateRevocationList $ cACertificate ) MAY crossCertificatePair )
This object class is used to augment entries for objects that act as certificate authorities, as defined in clause 6.18 of [X.521]. This object class is deprecated in favor of pkiCA.
( 2.5.6.16.2 NAME 'certificationAuthority-V2' DESC 'X.509 certificate authority, version 2' SUP certificationAuthority AUXILIARY MAY deltaRevocationList )
General certificate considerations [RFC3280] apply to LDAP-aware certificate applications. General LDAP security considerations [RFC4510] apply as well.
While elements of certificate information are commonly signed, these signatures only protect the integrity of the signed information. In the absence of data integrity protections in LDAP (or lower layer, e.g., IPsec), a server is not assured that client certificate request (or other request) was unaltered in transit. Likewise, a client cannot be assured that the results of the query were unaltered in
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transit. Hence, it is generally recommended that implementations make use of authentication and data integrity services in LDAP [RFC4513][RFC4511].
The IANA has registered an LDAP Object Identifier [RFC4520] for use in this technical specification.
Subject: Request for LDAP OID Registration Person & email address to contact for further information: Kurt Zeilenga <kurt@OpenLDAP.org> Specification: RFC 4523 Author/Change Controller: IESG Comments: Identifies the LDAP X.509 Certificate schema elements introduced in this document.
The IANA has updated the LDAP Descriptor registry [RFC44520] as indicated below.
Subject: Request for LDAP Descriptor Registration Descriptor (short name): see table Object Identifier: see table Person & email address to contact for further information: Kurt Zeilenga <kurt@OpenLDAP.org> Usage: see table Specification: RFC 4523 Author/Change Controller: IESG
algorithmIdentifierMatch M 2.5.13.40 authorityRevocationList A 2.5.4.38 * cACertificate A 2.5.4.37 * cRLDistributionPoint O 2.5.6.19 * certificateExactMatch M 2.5.13.34 certificateListExactMatch M 2.5.13.38 certificateListMatch M 2.5.13.39 certificateMatch M 2.5.13.35 certificatePairExactMatch M 2.5.13.36 certificatePairMatch M 2.5.13.37 certificateRevocationList A 2.5.4.39 * certificationAuthority O 2.5.6.16 * certificationAuthority-V2 O 2.5.6.16.2 * crossCertificatePair A 2.5.4.40 *
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deltaCRL O 2.5.6.23 * deltaRevocationList A 2.5.4.53 * pkiCA O 2.5.6.22 * pkiUser O 2.5.6.21 * strongAuthenticationUser O 2.5.6.15 * supportedAlgorithms A 2.5.4.52 * userCertificate A 2.5.4.36 * userSecurityInformation O 2.5.6.18 *
This document is based on X.509, a product of the ITU-T. A number of LDAP schema definitions were based on those found in RFCs 2252 and 2256, both products of the IETF ASID WG. The ABNF productions in Appendix A were provided by Steven Legg. Additional material was borrowed from prior works by David Chadwick and Steven Legg to refine the LDAP X.509 schema.
[RFC1777] Yeong, W., Howes, T., and S. Kille, "Lightweight Directory Access Protocol", RFC 1777, March 1995.
[RFC2156] Kille, S., "MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIME", RFC 2156, January 1998.
[RFC3280] Housley, R., Polk, W., Ford, W., and D. Solo, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 3280, April 2002.
[RFC3494] Zeilenga, K., "Lightweight Directory Access Protocol version 2 (LDAPv2) to Historic Status", RFC 3494, March 2003.
[RFC3642] Legg, S., "Common Elements of Generic String Encoding Rules (GSER) Encodings", RFC 3642, October 2003.
[RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005.
[RFC4511] Sermersheim, J., Ed., "Lightweight Directory Access Protocol (LDAP): The Protocol", RFC 4511, June 2006.
[RFC4513] Harrison, R. Ed., "Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms", RFC 4513, June 2006.
[RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)", BCP 64, RFC 4520, June 2006.
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Appendix A.
This appendix is informative.
This appendix provides ABNF [RFC4234] grammars for GSER-based [RFC3641] LDAP-specific encodings specified in this document. These grammars where produced using, and relying on, Common Elements for GSER Encodings [RFC3642].
;; Note: The <ORAddress> rule encodes the x400Address component ;; of a GeneralName as a character string between double quotes. ;; The character string is first derived according to Section 4.1 ;; of [RFC2156], and then any embedded double quotes are escaped ;; by being repeated. This resulting string is output between ;; double quotes.
CertificatePairExactAssertion = "{" [ sp cpea-issuedTo ] [sep sp cpea-issuedBy ] sp "}" ;; At least one of <cpea-issuedTo> or <cpea-issuedBy> MUST be present.
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