Network Working Group
Request for Comments: 4530
Category: Standards Track

K. Zeilenga
OpenLDAP Foundation
June 2006

Lightweight Directory Access Protocol (LDAP)

entryUUID Operational Attribute

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

Abstract

This document describes the LDAP/X.500 'entryUUID' operational attribute and associated matching rules and syntax. The attribute holds a server-assigned Universally Unique Identifier (UUID) for the object. Directory clients may use this attribute to distinguish objects identified by a distinguished name or to locate an object after renaming.

   1. Background and Intended Use .....................................2
   2. UUID Schema Elements ............................................3
      2.1. UUID Syntax ................................................3
      2.2. 'uuidMatch' Matching Rule ..................................3
      2.3. 'uuidOrderingMatch' Matching Rule ..........................3
      2.4. 'entryUUID' Attribute ......................................4
   3. Security Considerations .........................................4
   4. IANA Considerations .............................................5
      4.1. Object Identifier Registration .............................5
      4.2. UUID Syntax Registration ...................................5
      4.3. 'uuidMatch' Descriptor Registration ........................5
      4.4. 'uuidOrderingMatch' Descriptor Registration ................5
      4.5. 'entryUUID' Descriptor Registration ........................6
   5. Acknowledgements ................................................6
   6. References ......................................................6
      6.1. Normative References .......................................6
      6.2. Informative References .....................................7

1. Background and Intended Use

In X.500 Directory Services [X.501], such as those accessible using the Lightweight Directory Access Protocol (LDAP) [RFC4510], an object is identified by its distinguished name (DN). However, DNs are not stable identifiers. That is, a new object may be identified by a DN that previously identified another (now renamed or deleted) object.

A Universally Unique Identifier (UUID) is "an identifier unique across both space and time, with respect to the space of all UUIDs" [RFC4122]. UUIDs are used in a wide range of systems.

This document describes the 'entryUUID' operational attribute, which holds the UUID assigned to the object by the server. Clients may use this attribute to distinguish objects identified by a particular distinguished name or to locate a particular object after renaming.

This document defines the UUID syntax, the 'uuidMatch' and 'uuidOrderingMatch' matching rules, and the 'entryUUID' attribute type.

Schema definitions are provided using LDAP description formats [RFC4512]. Definitions provided here are formatted (line wrapped) for readability.

In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14 [RFC2119].

2. UUID Schema Elements

2.1. UUID Syntax

A Universally Unique Identifier (UUID) [RFC4122] is a 16-octet (128- bit) value that identifies an object. The ASN.1 [X.680] type UUID is defined to represent UUIDs as follows:

       UUID ::= OCTET STRING (SIZE(16))
             -- constrained to an UUID [RFC4122]

In LDAP, UUID values are encoded using the [ASCII] character string representation described in [RFC4122]. For example, "597ae2f6-16a6-1027-98f4-d28b5365dc14".

The following is an LDAP syntax description suitable for publication in subschema subentries.

       ( 1.3.6.1.1.16.1 DESC 'UUID' )

2.2. 'uuidMatch' Matching Rule

The 'uuidMatch' matching rule compares an asserted UUID with a stored UUID for equality. Its semantics are the same as the 'octetStringMatch' [X.520][RFC4517] matching rule. The rule differs from 'octetStringMatch' in that the assertion value is encoded using the UUID string representation instead of the normal OCTET STRING string representation.

The following is an LDAP matching rule description suitable for publication in subschema subentries.

( 1.3.6.1.1.16.2 NAME 'uuidMatch'

           SYNTAX 1.3.6.1.1.16.1 )

2.3. 'uuidOrderingMatch' Matching Rule

The 'uuidOrderingMatch' matching rule compares an asserted UUID with a stored UUID for ordering. Its semantics are the same as the 'octetStringOrderingMatch' [X.520][RFC4517] matching rule. The rule differs from 'octetStringOrderingMatch' in that the assertion value is encoded using the UUID string representation instead of the normal OCTET STRING string representation.

The following is an LDAP matching rule description suitable for publication in subschema subentries.

( 1.3.6.1.1.16.3 NAME 'uuidOrderingMatch'

           SYNTAX 1.3.6.1.1.16.1 )

Note that not all UUID variants have a defined ordering; and even where it does, servers are not obligated to assign UUIDs in any particular order. This matching rule is provided for completeness.

2.4. 'entryUUID' Attribute

The 'entryUUID' operational attribute provides the Universally Unique Identifier (UUID) assigned to the entry.

The following is an LDAP attribute type description suitable for publication in subschema subentries.

( 1.3.6.1.1.16.4 NAME 'entryUUID': DESC 'UUID of the entry'
EQUALITY uuidMatch
ORDERING uuidOrderingMatch
SYNTAX 1.3.6.1.1.16.1
SINGLE-VALUE
NO-USER-MODIFICATION
USAGE directoryOperation )

Servers SHALL generate and assign a new UUID to each entry upon its addition to the directory and provide that UUID as the value of the 'entryUUID' operational attribute. An entry's UUID is immutable.

UUID are to be generated in accordance with Section 4 of [RFC4122]. In particular, servers MUST ensure that each generated UUID is unique in space and time.

3. Security Considerations

An entry's relative distinguish name (RDN) is composed from attribute values of the entry, which are commonly descriptive of the object the entry represents. Although deployers are encouraged to use naming attributes whose values are widely disclosable [RFC4514], entries are often named using information that cannot be disclosed to all parties. As UUIDs do not contain any descriptive information of the object they identify, UUIDs may be used to identify a particular entry without disclosure of its contents.

General UUID security considerations [RFC4122] apply.

General LDAP security considerations [RFC4510] apply.

4. IANA Considerations

The IANA has registered the LDAP values [RFC4520] specified in this document.

4.1. Object Identifier Registration

       Subject: Request for LDAP OID Registration
       Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
       Specification: RFC 4530
       Author/Change Controller: IESG
       Comments:
           Identifies the UUID schema elements

4.2. UUID Syntax Registration

       Subject: Request for LDAP Syntax Registration
       Object Identifier: 1.3.6.1.1.16.1
       Description: UUID
       Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
       Specification: RFC 4530
       Author/Change Controller: IESG
       Comments:
            Identifies the UUID syntax

4.3. 'uuidMatch' Descriptor Registration

       Subject: Request for LDAP Descriptor Registration
       Descriptor (short name): uuidMatch
       Object Identifier: 1.3.6.1.1.16.2
       Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
       Usage: Matching Rule
       Specification: RFC 4530
       Author/Change Controller: IESG

4.4. 'uuidOrderingMatch' Descriptor Registration

       Subject: Request for LDAP Descriptor Registration
       Descriptor (short name): uuidOrderingMatch
       Object Identifier: 1.3.6.1.1.16.3
       Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
       Usage: Matching Rule
       
       Specification: RFC 4530
       Author/Change Controller: IESG

4.5. 'entryUUID' Descriptor Registration

The IANA has registered the LDAP 'entryUUID' descriptor.

       Subject: Request for LDAP Descriptor Registration
       Descriptor (short name): entryUUID
       Object Identifier: 1.3.6.1.1.16.4
       Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
       Usage: Attribute Type
       Specification: RFC 4530
       Author/Change Controller: IESG

5. Acknowledgements

This document is based upon discussions in the LDAP Update and Duplication Protocols (LDUP) WG. Members of the LDAP Directorate provided review.

6. References

6.1. Normative References

   [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.
   
   [RFC4122]     Leach, P., Mealling, M., and R. Salz, "A Universally
                 Unique IDentifier (UUID) URN Namespace", RFC 4122, July
                 2005.
   
   [RFC4510]     Zeilenga, K., Ed., "Lightweight Directory Access
                 Protocol (LDAP): Technical Specification Road Map", RFC
                 4510, June 2006.
   
   [RFC4512]     Zeilenga, K., "Lightweight Directory Access Protocol
                 (LDAP): Directory Information Models", RFC 4512, June
                 2006.
   
   [RFC4517]     Legg, S., Ed., "Lightweight Directory Access Protocol
                 (LDAP): Syntaxes and Matching Rules", RFC 4517, June
                 2006.
   
   [ASCII]       Coded Character Set--7-bit American Standard Code for
                 Information Interchange, ANSI X3.4-1986.
   
   [X.501]       International Telecommunication Union -
                 Telecommunication Standardization Sector, "The
                 Directory -- Models," X.501(1993) (also ISO/IEC 9594-
                 2:1994).
   
   [X.520]       International Telecommunication Union -
                 Telecommunication Standardization Sector, "The
                 Directory: Selected Attribute Types", X.520(1993) (also
                 ISO/IEC 9594-6:1994).
   
   [X.680]       International Telecommunication Union -
                 Telecommunication Standardization Sector, "Abstract
                 Syntax Notation One (ASN.1) - Specification of Basic
                 Notation", X.680(2002) (also ISO/IEC 8824-1:2002).

6.2. Informative References

   [RFC4514]     Zeilenga, K., Ed., "Lightweight Directory Access
                 Protocol (LDAP): String Representation of Distinguished
                 Names", RFC 4514, June 2006.
   
   [RFC4520]     Zeilenga, K., "Internet Assigned Numbers Authority
                 (IANA) Considerations for the Lightweight Directory
                 Access Protocol (LDAP)", BCP 64, RFC 4520, June 2006.

Author's Address

Kurt D. Zeilenga
OpenLDAP Foundation

EMail:

          Kurt@OpenLDAP.org

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