Information technology — Open systems interconnection — Part 3: The Directory: Abstract service definition

This document defines in an abstract way the externally visible service provided by the Directory. This document does not specify individual implementations or products.

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Publication Date
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6060 - International Standard published
Start Date
01-Dec-2020
Completion Date
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INTERNATIONAL ISO/IEC
STANDARD 9594-3
Ninth edition
2020-11
Information technology — Open
systems interconnection —
Part 3:
The Directory: Abstract service
definition
Reference number
ISO/IEC 9594-3:2020(E)
ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC 9594-3:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 9594-3:2020(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that are

members of ISO or IEC participate in the development of International Standards through technical

committees established by the respective organization to deal with particular fields of technical activity.

ISO and IEC technical committees collaborate in fields of mutual interest. Other international

organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the

work.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of document should be noted (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. Details

of any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC list of patent

declarations received (see http://patents.iec.ch).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the World

Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT),
see www.iso.org/iso/foreword.html.

This document was prepared by ITU-T as ITU-T X.511 (10/2019) and drafted in accordance with

its editorial rules, in collaboration with Joint Technical Committee ISO/IEC JTC 1,

Information technology, Subcommittee SC 6, Telecommunications and information exchange between

systems.

This ninth edition cancels and replaces the eighth edition (ISO/IEC 9594-3:2017), which has been

technically revised.
A list of all parts in the ISO/IEC 9594 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body.

A complete listing of these bodies can be found at www.iso.org/members.html.
© ISO/IEC 2020 – All rights reserved iii
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ISO/IEC 9594-3:2020 (E)
CONTENTS
Page

1 Scope .............................................................................................................................................................. 1

2 Normative references...................................................................................................................................... 1

2.1 Identical Recommendations | International Standards ........................................................................ 1

2.2 Paired Recommendations | International Standards equivalent in technical content ........................... 1

2.3 Additional references .......................................................................................................................... 2

3 Definitions ...................................................................................................................................................... 2

3.1 OSI Reference Model security architecture definitions....................................................................... 2

3.2 Basic Directory definitions .................................................................................................................. 2

3.3 Directory model definitions ................................................................................................................ 2

3.4 Directory information base definitions ................................................................................................ 2

3.5 Directory entry definitions .................................................................................................................. 2

3.6 Name definitions ................................................................................................................................. 3

3.7 Distributed operations definitions ....................................................................................................... 3

3.8 Abstract service definitions ................................................................................................................. 3

4 Abbreviations ................................................................................................................................................. 4

5 Conventions .................................................................................................................................................... 4

6 Overview of the Directory service .................................................................................................................. 5

7 Information types and common procedures ................................................................................................... 5

7.1 Introduction ......................................................................................................................................... 5

7.2 Information types defined elsewhere .................................................................................................. 5

7.3 Common arguments ............................................................................................................................ 6

7.4 Common results .................................................................................................................................. 9

7.5 Service controls ................................................................................................................................... 10

7.6 Entry information selection ................................................................................................................. 12

7.7 Entry information ................................................................................................................................ 15

7.8 Filter .................................................................................................................................................... 17

7.9 Paged results........................................................................................................................................ 20

7.10 Security parameters ............................................................................................................................. 22

7.11 Common elements of procedure for access control ............................................................................. 23

7.12 Managing the DSA Information Tree ................................................................................................. 25

7.13 Procedures for families of entries ........................................................................................................ 25

8 Directory authentication ................................................................................................................................. 26

8.1 Simple authentication procedure ......................................................................................................... 26

8.2 Password policy .................................................................................................................................. 28

9 Bind, Unbind operations, Change Password and Administer Password operations ....................................... 31

9.1 Directory Bind ..................................................................................................................................... 31

9.2 Directory Unbind ................................................................................................................................ 34

10 Directory Read operations .............................................................................................................................. 34

10.1 Read .................................................................................................................................................... 34

10.2 Compare .............................................................................................................................................. 37

10.3 Abandon .............................................................................................................................................. 40

11 Directory Search operations ........................................................................................................................... 40

11.1 List ...................................................................................................................................................... 40

11.2 Search .................................................................................................................................................. 44

12 Directory Modify operations .......................................................................................................................... 55

12.1 Add Entry ............................................................................................................................................ 55

12.2 Remove Entry...................................................................................................................................... 57

12.3 Modify Entry ....................................................................................................................................... 59

12.4 Modify DN .......................................................................................................................................... 63

12.5 Change Password ................................................................................................................................ 65

12.6 Administer Password........................................................................................................................... 66

© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.511 (10/2019) v
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ISO/IEC 9594-3:2020 (E)
Page

13 Operations for LDAP messages ..................................................................................................................... 66

13.1 LDAP Transport operation .................................................................................................................. 67

13.2 Linked LDAP operation ...................................................................................................................... 69

14 Errors .............................................................................................................................................................. 69

14.1 Error precedence ................................................................................................................................. 69

14.2 Abandoned .......................................................................................................................................... 70

14.3 Abandon Failed ................................................................................................................................... 70

14.4 Attribute Error ..................................................................................................................................... 71

14.5 Name Error .......................................................................................................................................... 72

14.6 Referral ................................................................................................................................................ 73

14.7 Security Error ...................................................................................................................................... 73

14.8 Service Error ....................................................................................................................................... 74

14.9 Update Error ........................................................................................................................................ 76

15 Analysis of search arguments ......................................................................................................................... 77

15.1 General check of search filter .............................................................................................................. 78

15.2 Check of request-attribute-profiles ...................................................................................................... 79

15.3 Check of controls and hierarchy selections ......................................................................................... 80

15.4 Check of matching use ........................................................................................................................ 81

Annex A – Abstract Service in ASN.1 ...................................................................................................................... 82

Annex B – Operational semantics for Basic Access Control ..................................................................................... 98

Annex C – Examples of searching families of entries ............................................................................................... 111

C.1 Single family example ......................................................................................................................... 111

C.2 Multiple families example ................................................................................................................... 112

Annex D – External ASN.1 module .......................................................................................................................... 115

Annex E – Use of protected passwords for Bind operations ..................................................................................... 119

Annex F – Amendments and corrigenda ................................................................................................................... 120

© ISO/IEC 2020 – All rights reserved
vi Rec. ITU-T X.511 (10/2019)
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ISO/IEC 9594-3:2020 (E)
Introduction

This Recommendation | International Standard, together with the other Recommendations | International Standards, has

been produced to facilitate the interconnection of information processing systems to provide directory services. A set of

such systems, together with the directory information that they hold, can be viewed as an integrated whole, called the

Directory. The information held by the Directory, collectively known as the Directory Information Base (DIB), is

typically used to facilitate communication between, with or about objects such as application entities, people, terminals,

and distribution lists.

The Directory plays a significant role in Open Systems Interconnection, whose aim is to allow, with a minimum of

technical agreement outside of the interconnection standards themselves, the interconnection of information processing

systems:
– from different manufacturers;
– under different managements;
– of different levels of complexity; and
– of different ages.

This Recommendation | International Standard defines the capabilities provided by the Directory to its users.

This Recommendation | International Standard provides the foundation frameworks upon which industry profiles can be

defined by other standards groups and industry forums. Many of the features defined as optional in these frameworks may

be mandated for use in certain environments through profiles. This ninth edition technically revises and enhances the

eighth edition of this Recommendation | International Standard.
This ninth edition specifies versions 1 and 2 of the Directory protocols.

Rec. ITU-T X.511 (1993) | ISO/IEC 9594-3 (1995), Rec. ITU-T X.518 (1993) | ISO/IEC 9594-4 (1995) and Rec.

ITU-T X.519 (1993) | ISO/IEC 9594-5 (1995) and their previous edition specified only version 1. Most of the services

and protocols specified in this edition are designed to function under version 1. However, some enhanced services and

protocols, e.g., signed errors, will not function unless all Directory entities involved in the operation have negotiated

version 2. Whichever version has been negotiated, differences between the services and between the protocols defined in

the nine editions, except for those specifically assigned to version 2, are accommodated using the rules of extensibility

defined in Rec. ITU-T X.519 | ISO/IEC 9594-5.

Annex A, which is an integral part of this Recommendation | International Standard, provides the ASN.1 module for the

Directory abstract service.

Annex B, which is not an integral part of this Recommendation | International Standard, provides charts that describe the

semantics associated with Basic Access Control as it applies to the processing of a Directory operation.

Annex C, which is not an integral part of this Recommendation | International Standard, gives examples of the use of

families of entries.

Annex D, which is not an integral part of this Recommendation | International Standard, includes an updated copy of an

external ASN.1 module referenced by this Directory Specification.

Annex E, which is not an integral part of this Recommendation | International Standard, provides a suggested technique

for Bind protected password.

Annex F, which is not an integral part of this Recommendation | International Standard, lists the amendments and defect

reports that have been incorporated to form this edition of this Recommendation | International Standard.

© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.511 (10/2019) vii
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© ISO/IEC 2020 – All rights reserved
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ISO/IEC 9594-3:2020 (E)
INTERNATIONAL STANDARD
ITU-T RECOMMENDATION
Information technology – Open Systems Interconnection – The Directory:
Abstract service definition
1 Scope

This Recommendation | International Standard defines in an abstract way the externally visible service provided by the

Directory.

This Recommendation | International Standard does not specify individual implementations or products.

2 Normative references

The following Recommendations and International Standards contain provisions which, through reference in this text,

constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated

were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this

Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent edition

of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently valid

International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently valid

ITU-T Recommendations.
2.1 Identical Recommendations | International Standards

– Recommendation ITU-T X.500 (2019) | ISO/IEC 9594-1:2020, Information technology – Open Systems

Interconnection – The Directory: Overview of concepts, models and services.

– Recommendation ITU-T X.501 (2019) | ISO/IEC 9594-2:2020, Information technology – Open Systems

Interconnection – The Directory: Models.

– Recommendation ITU-T X.509 (2019) | ISO/IEC 9594-8:2020, Information technology – Open Systems

Interconnection – The Directory: Public-key and attribute certificate frameworks.

– Recommendation ITU-T X.518 (2019) | ISO/IEC 9594-4:2020, Information technology – Open Systems

Interconnection – The Directory: Procedures for distributed operation.

– Recommendation ITU-T X.519 (2019) | ISO/IEC 9594-5:2020, Information technology – Open Systems

Interconnection – The Directory: Protocol specifications.

– Recommendation ITU-T X.520 (2019) | ISO/IEC 9594-6:2020, Information technology – Open Systems

Interconnection – The Directory: Selected attribute types.

– Recommendation ITU-T X.521 (2019) | ISO/IEC 9594-7:2020, Information technology – Open Systems

Interconnection – The Directory: Selected object classes.

– Recommendation ITU-T X.525 (2019) | ISO/IEC 9594-9:2020, Information technology – Open Systems

Interconnection – The Directory: Replication.

– Recommendation ITU-T X.680 (2015) | ISO/IEC 8824-1:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Specification of basic notation.

– Recommendation ITU-T X.681 (2015) | ISO/IEC 8824-2:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Information object specification.

– Recommendation ITU-T X.682 (2015) | ISO/IEC 8824-3:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Constraint specification.

– Recommendation ITU-T X.683 (2015) | ISO/IEC 8824-4:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Parameterization of ASN.1 specifications.

2.2 Paired Recommendations | International Standards equivalent in technical content

– Recommendation ITU-T X.800 (1991), Security architecture for Open Systems Interconnection for CCITT

applications.

ISO 7498-2:1989, Information processing systems – Open Systems Interconnection – Basic Reference

Model – Part 2: Security Architecture.
© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.511 (10/2019) 1
---------------------- Page: 8 ----------------------
ISO/IEC 9594-3:2020 (E)
2.3 Additional references

– Recommendation ITU-T X.200 (1994) | ISO/IEC 7498-1:1994, Information technology – Open Systems

Interconnection – Basic Reference Model: The basic model.
– IETF RFC 2025 (1996), The Simple Public-Key GSS-API Mechanism (SPKM).
– IETF RFC 4422 (2006), Simple Authentication and Security Layer (SASL).

– IETF RFC 4511 (2006), Lightweight Directory Access Protocol (LDAP): The Protocol.

3 Definitions

For the purposes of this Recommendation | International Standard, the following definitions apply.

3.1 OSI Reference Model security architecture definitions
The following terms are defined in Rec. ITU-T X.800 | ISO 7498-2:
a) password.
3.2 Basic Directory definitions
The following terms are defined in Rec. ITU-T X.500 | ISO/IEC 9594-1:
a) Directory;
b) Directory Information Base;
c) (Directory) User.
3.3 Directory model definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) Directory System Agent;
b) Directory User Agent.
3.4 Directory information base definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) alias entry;
b) ancestor;
c) compound entry;
d) (Directory) entry;
e) Directory Information Tree;
f) family (of entries);
g) immediate superior;
h) immediately superior entry/object;
i) object;
j) object class;
k) object entry;
l) subordinate;
m) superior.
3.5 Directory entry definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) attribute;
b) attribute type;
c) attribute value;
© ISO/IEC 2020 – All rights reserved
2 Rec. ITU-T X.511 (10/2019)
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ISO/IEC 9594-3:2020 (E)
d) attribute value assertion;
e) context;
f) context type;
g) context value;
h) operational attribute;
i) matching rule;
j) user attribute.
3.6 Name definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) alias, alias name;
b) distinguished name;
c) (directory) name;
d) purported name;
e) relative distinguished name.
3.7 Distributed operations definitions
The following terms are defined in Rec. ITU-T X.518 | ISO/IEC 9594-4:
a) bound DSA;
b) chaining;
c) initial performer;
d) LDAP requester;
e) referral.
3.8 Abstract service definitions

For the purposes of this Recommendation | International Standard, the following definitions apply.

3.8.1 additional search: A search that starts from joinBaseObject as specified by the originator in the search

request.

3.8.2 contributing member: A family member within a compound entry, which has made a contribution to either a

Read, Search or Modify Entry operation.

3.8.3 explicitly unmarked entry: An entry or a family member that is excluded from the SearchResult according

to a specification given in a control attribute referenced by the governing-search-rule.

3.8.4 family grouping: A set of members of a compound attribute that are grouped together for the purpose of

operation evaluation.

3.8.5 filter: An assertion about the presence or value of certain attributes of an entry in order to limit the scope of a

search.
3.8.6 originator: The user that originated an operation.

3.8.7 participating member: A family member that is either a contributing member or is a member of a family

grouping that as a whole matched a search filter.

3.8.8 Password expiration: The situation where a user password has reached the end of its validity period: the

account is locked and the user has to change the password before doing any other directory operation.

3.8.9 Password quality attributes: Attributes that specify how a password shall be constructed. Password quality

attributes include things like minimum length, mixture of characters (uppercase, lowercase, figures, punctuations, etc),

and avoidance of trivial passwords.

3.8.10 Password history: List of old passwords and the times they were inserted in the history.

3.8.11 primary search: The search that starts from baseObject as specified by the originator in the search request.

© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.511 (10/2019) 3
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ISO/IEC 9594-3:2020 (E)

3.8.12 relaxation: A progressive modification of the behaviour of a filter during a search operation so as to achieve

more matched entries if too few are received, or fewer matched entries if too many are received.

3.8.13 reply: A DAP/DSP result or an error; or an LDAP result.

3.8.14 request: Information consisting of an operation code and associated components to convey a directory operation

from a requester to a performer.

3.8.15 requester: A DUA, an LDAP client or a DSA sending a request to perform (i.e., invoke) an operation.

3.8.16 service controls: Parameters conveyed as part of an operation, which constrain various aspects of its

performance.

3.8.17 strand: A family grouping comprising all the members in a path from a leaf family member up to the ancestor

inclusive. A family member will reside in as many strands as there are leaf family members below it (as immediate or

non-immediate subordinates).
4 Abbreviations

For the purposes of this Recommendation | International Standard, the following abbreviations apply:

ACI Access Control Information
AVA Attribute Value Assertion
DIB Directory Information Base
DIT Directory Information Tree
DMD Directory Management Domain
DSA Directory System Agent
DUA Directory User Agent
LDAP Lightweight Directory Access Protocol
RDN Relative Distinguished Name
5 Conventions

The term "Directory Specification" (as in "this Directory Specification") shall be taken to mean Rec. ITU-T X.511 |

ISO/IEC 9594-3. The term "Directory Specifications" shall be taken to mean the Rec. ITU-T X.500 | ISO/IEC 9594-1,

Rec. ITU-T X.501 | ISO/IEC 9594-2, Rec. ITU-T X.511 | ISO/IEC 9594-3, Rec. ITU-T X.518 | ISO/IEC 9594-4, Rec.

ITU-T X.519 | ISO/IEC 9594-5, Rec. ITU-T X.520 | ISO/IEC 9594-6, Rec ITU-T X.521 | ISO/IEC 9594-7 and Rec. ITU-

T X.525 | ISO/IEC 9594-9.

If an International Standard or ITU-T Recommendation is referenced within normal text without an indication of the

edition, the edition shall be taken to be the latest one as specified in the normative references clause.

Prior to year 2020, the parts making up the Directory Specifications progressed together and can therefore collectively be

identified as the Directory Specifications of a specific edition using the format: Rec. ITU-T X.5** (yyyy) | ISO/IEC 9594-

*:yyyy (e.g.; Rec ITU-T X.5** (1993) | ISO/IEC 9594-*:1995).

This Directory Specification makes extensive use of Abstract Syntax Notation One (ASN.1) for the formal specification

of data types and values, as it is specified in Rec. ITU-T X.680 | ISO/IEC 8824-1, ITU-T X.681 (2015) | ISO/IEC 8824-

2, ITU-T X.682 (2015) | ISO/
...

INTERNATIONAL ISO/IEC
STANDARD 9594-3
Ninth edition
Information technology — Open
systems interconnection —
Part 3:
The Directory: Abstract service
definition
PROOF/ÉPREUVE
Reference number
ISO/IEC 9594-3:2020(E)
© ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC 9594-3:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO/IEC 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 9594-3:2020(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that are

members of ISO or IEC participate in the development of International Standards through technical

committees established by the respective organization to deal with particular fields of technical activity.

ISO and IEC technical committees collaborate in fields of mutual interest. Other international

organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the

work.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of document should be noted (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. Details

of any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC list of patent

declarations received (see http://patents.iec.ch).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the World

Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT),
see www.iso.org/iso/foreword.html.

This document was prepared by ITU-T as ITU-T X.511 (10/2019) and drafted in accordance with its

editorial rules. It was adopted by Joint Technical Committee ISO/IEC JTC 1, Information technology,

Subcommittee SC 6, Telecommunications and information exchange between systems.
A list of all parts in the ISO/IEC 9594 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO/IEC 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/IEC 9594-3:2020 (E)
CONTENTS
Page

1 Scope .............................................................................................................................................................. 1

2 Normative references...................................................................................................................................... 1

2.1 Identical Recommendations | International Standards ........................................................................ 1

2.2 Paired Recommendations | International Standards equivalent in technical content ........................... 1

2.3 Additional references .......................................................................................................................... 2

3 Definitions ...................................................................................................................................................... 2

3.1 OSI Reference Model security architecture definitions....................................................................... 2

3.2 Basic Directory definitions .................................................................................................................. 2

3.3 Directory model definitions ................................................................................................................ 2

3.4 Directory information base definitions ................................................................................................ 2

3.5 Directory entry definitions .................................................................................................................. 2

3.6 Name definitions ................................................................................................................................. 3

3.7 Distributed operations definitions ....................................................................................................... 3

3.8 Abstract service definitions ................................................................................................................. 3

4 Abbreviations ................................................................................................................................................. 4

5 Conventions .................................................................................................................................................... 4

6 Overview of the Directory service .................................................................................................................. 5

7 Information types and common procedures ................................................................................................... 5

7.1 Introduction ......................................................................................................................................... 5

7.2 Information types defined elsewhere .................................................................................................. 5

7.3 Common arguments ............................................................................................................................ 6

7.4 Common results .................................................................................................................................. 9

7.5 Service controls ................................................................................................................................... 10

7.6 Entry information selection ................................................................................................................. 12

7.7 Entry information ................................................................................................................................ 15

7.8 Filter .................................................................................................................................................... 17

7.9 Paged results........................................................................................................................................ 20

7.10 Security parameters ............................................................................................................................. 22

7.11 Common elements of procedure for access control ............................................................................. 23

7.12 Managing the DSA Information Tree ................................................................................................. 25

7.13 Procedures for families of entries ........................................................................................................ 25

8 Directory authentication ................................................................................................................................. 26

8.1 Simple authentication procedure ......................................................................................................... 26

8.2 Password policy .................................................................................................................................. 28

9 Bind, Unbind operations, Change Password and Administer Password operations ....................................... 31

9.1 Directory Bind ..................................................................................................................................... 31

9.2 Directory Unbind ................................................................................................................................ 34

10 Directory Read operations .............................................................................................................................. 34

10.1 Read .................................................................................................................................................... 34

10.2 Compare .............................................................................................................................................. 37

10.3 Abandon .............................................................................................................................................. 40

11 Directory Search operations ........................................................................................................................... 40

11.1 List ...................................................................................................................................................... 40

11.2 Search .................................................................................................................................................. 44

12 Directory Modify operations .......................................................................................................................... 55

12.1 Add Entry ............................................................................................................................................ 55

12.2 Remove Entry...................................................................................................................................... 57

12.3 Modify Entry ....................................................................................................................................... 59

12.4 Modify DN .......................................................................................................................................... 63

12.5 Change Password ................................................................................................................................ 65

12.6 Administer Password........................................................................................................................... 66

© ISO/IEC 2020 – All rights reserved
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ISO/IEC 9594-3:2020 (E)
Page

13 Operations for LDAP messages ..................................................................................................................... 66

13.1 LDAP Transport operation .................................................................................................................. 67

13.2 Linked LDAP operation ...................................................................................................................... 69

14 Errors .............................................................................................................................................................. 69

14.1 Error precedence ................................................................................................................................. 69

14.2 Abandoned .......................................................................................................................................... 70

14.3 Abandon Failed ................................................................................................................................... 70

14.4 Attribute Error ..................................................................................................................................... 71

14.5 Name Error .......................................................................................................................................... 72

14.6 Referral ................................................................................................................................................ 73

14.7 Security Error ...................................................................................................................................... 73

14.8 Service Error ....................................................................................................................................... 74

14.9 Update Error ........................................................................................................................................ 76

15 Analysis of search arguments ......................................................................................................................... 77

15.1 General check of search filter .............................................................................................................. 78

15.2 Check of request-attribute-profiles ...................................................................................................... 79

15.3 Check of controls and hierarchy selections ......................................................................................... 80

15.4 Check of matching use ........................................................................................................................ 81

Annex A – Abstract Service in ASN.1 ...................................................................................................................... 82

Annex B – Operational semantics for Basic Access Control ..................................................................................... 98

Annex C – Examples of searching families of entries ............................................................................................... 111

C.1 Single family example ......................................................................................................................... 111

C.2 Multiple families example ................................................................................................................... 112

Annex D – External ASN.1 module .......................................................................................................................... 115

Annex E – Use of protected passwords for Bind operations ..................................................................................... 119

Annex F – Amendments and corrigenda ................................................................................................................... 120

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ISO/IEC 9594-3:2020 (E)
Introduction

This Recommendation | International Standard, together with the other Recommendations | International Standards, has

been produced to facilitate the interconnection of information processing systems to provide directory services. A set of

such systems, together with the directory information that they hold, can be viewed as an integrated whole, called the

Directory. The information held by the Directory, collectively known as the Directory Information Base (DIB), is

typically used to facilitate communication between, with or about objects such as application entities, people, terminals,

and distribution lists.

The Directory plays a significant role in Open Systems Interconnection, whose aim is to allow, with a minimum of

technical agreement outside of the interconnection standards themselves, the interconnection of information processing

systems:
– from different manufacturers;
– under different managements;
– of different levels of complexity; and
– of different ages.

This Recommendation | International Standard defines the capabilities provided by the Directory to its users.

This Recommendation | International Standard provides the foundation frameworks upon which industry profiles can be

defined by other standards groups and industry forums. Many of the features defined as optional in these frameworks may

be mandated for use in certain environments through profiles. This ninth edition technically revises and enhances the

eighth edition of this Recommendation | International Standard.
This ninth edition specifies versions 1 and 2 of the Directory protocols.

Rec. ITU-T X.511 (1993) | ISO/IEC 9594-3 (1995), Rec. ITU-T X.518 (1993) | ISO/IEC 9594-4 (1995) and Rec.

ITU-T X.519 (1993) | ISO/IEC 9594-5 (1995) and their previous edition specified only version 1. Most of the services

and protocols specified in this edition are designed to function under version 1. However, some enhanced services and

protocols, e.g., signed errors, will not function unless all Directory entities involved in the operation have negotiated

version 2. Whichever version has been negotiated, differences between the services and between the protocols defined in

the nine editions, except for those specifically assigned to version 2, are accommodated using the rules of extensibility

defined in Rec. ITU-T X.519 | ISO/IEC 9594-5.

Annex A, which is an integral part of this Recommendation | International Standard, provides the ASN.1 module for the

Directory abstract service.

Annex B, which is not an integral part of this Recommendation | International Standard, provides charts that describe the

semantics associated with Basic Access Control as it applies to the processing of a Directory operation.

Annex C, which is not an integral part of this Recommendation | International Standard, gives examples of the use of

families of entries.

Annex D, which is not an integral part of this Recommendation | International Standard, includes an updated copy of an

external ASN.1 module referenced by this Directory Specification.

Annex E, which is not an integral part of this Recommendation | International Standard, provides a suggested technique

for Bind protected password.

Annex F, which is not an integral part of this Recommendation | International Standard, lists the amendments and defect

reports that have been incorporated to form this edition of this Recommendation | International Standard.

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ISO/IEC 9594-3:2020 (E)
INTERNATIONAL STANDARD
ITU-T RECOMMENDATION
Information technology – Open Systems Interconnection – The Directory:
Abstract service definition
1 Scope

This Recommendation | International Standard defines in an abstract way the externally visible service provided by the

Directory.

This Recommendation | International Standard does not specify individual implementations or products.

2 Normative references

The following Recommendations and International Standards contain provisions which, through reference in this text,

constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated

were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this

Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent edition

of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently valid

International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently valid

ITU-T Recommendations.
2.1 Identical Recommendations | International Standards

– Recommendation ITU-T X.500 (2019) | ISO/IEC 9594-1:2020, Information technology – Open Systems

Interconnection – The Directory: Overview of concepts, models and services.

– Recommendation ITU-T X.501 (2019) | ISO/IEC 9594-2:2020, Information technology – Open Systems

Interconnection – The Directory: Models.

– Recommendation ITU-T X.509 (2019) | ISO/IEC 9594-8:2020, Information technology – Open Systems

Interconnection – The Directory: Public-key and attribute certificate frameworks.

– Recommendation ITU-T X.518 (2019) | ISO/IEC 9594-4:2020, Information technology – Open Systems

Interconnection – The Directory: Procedures for distributed operation.

– Recommendation ITU-T X.519 (2019) | ISO/IEC 9594-5:2020, Information technology – Open Systems

Interconnection – The Directory: Protocol specifications.

– Recommendation ITU-T X.520 (2019) | ISO/IEC 9594-6:2020, Information technology – Open Systems

Interconnection – The Directory: Selected attribute types.

– Recommendation ITU-T X.521 (2019) | ISO/IEC 9594-7:2020, Information technology – Open Systems

Interconnection – The Directory: Selected object classes.

– Recommendation ITU-T X.525 (2019) | ISO/IEC 9594-9:2020, Information technology – Open Systems

Interconnection – The Directory: Replication.

– Recommendation ITU-T X.680 (2015) | ISO/IEC 8824-1:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Specification of basic notation.

– Recommendation ITU-T X.681 (2015) | ISO/IEC 8824-2:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Information object specification.

– Recommendation ITU-T X.682 (2015) | ISO/IEC 8824-3:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Constraint specification.

– Recommendation ITU-T X.683 (2015) | ISO/IEC 8824-4:2015, Information technology – Abstract Syntax

Notation One (ASN.1): Parameterization of ASN.1 specifications.

2.2 Paired Recommendations | International Standards equivalent in technical content

– Recommendation ITU-T X.800 (1991), Security architecture for Open Systems Interconnection for CCITT

applications.

ISO 7498-2:1989, Information processing systems – Open Systems Interconnection – Basic Reference

Model – Part 2: Security Architecture.
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ISO/IEC 9594-3:2020 (E)
2.3 Additional references

– Recommendation ITU-T X.200 (1994) | ISO/IEC 7498-1:1994, Information technology – Open Systems

Interconnection – Basic Reference Model: The basic model.
– IETF RFC 2025 (1996), The Simple Public-Key GSS-API Mechanism (SPKM).
– IETF RFC 4422 (2006), Simple Authentication and Security Layer (SASL).

– IETF RFC 4511 (2006), Lightweight Directory Access Protocol (LDAP): The Protocol.

3 Definitions

For the purposes of this Recommendation | International Standard, the following definitions apply.

3.1 OSI Reference Model security architecture definitions
The following terms are defined in Rec. ITU-T X.800 | ISO 7498-2:
a) password.
3.2 Basic Directory definitions
The following terms are defined in Rec. ITU-T X.500 | ISO/IEC 9594-1:
a) Directory;
b) Directory Information Base;
c) (Directory) User.
3.3 Directory model definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) Directory System Agent;
b) Directory User Agent.
3.4 Directory information base definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) alias entry;
b) ancestor;
c) compound entry;
d) (Directory) entry;
e) Directory Information Tree;
f) family (of entries);
g) immediate superior;
h) immediately superior entry/object;
i) object;
j) object class;
k) object entry;
l) subordinate;
m) superior.
3.5 Directory entry definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) attribute;
b) attribute type;
c) attribute value;
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ISO/IEC 9594-3:2020 (E)
d) attribute value assertion;
e) context;
f) context type;
g) context value;
h) operational attribute;
i) matching rule;
j) user attribute.
3.6 Name definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) alias, alias name;
b) distinguished name;
c) (directory) name;
d) purported name;
e) relative distinguished name.
3.7 Distributed operations definitions
The following terms are defined in Rec. ITU-T X.518 | ISO/IEC 9594-4:
a) bound DSA;
b) chaining;
c) initial performer;
d) LDAP requester;
e) referral.
3.8 Abstract service definitions

For the purposes of this Recommendation | International Standard, the following definitions apply.

3.8.1 additional search: A search that starts from joinBaseObject as specified by the originator in the search

request.

3.8.2 contributing member: A family member within a compound entry, which has made a contribution to either a

Read, Search or Modify Entry operation.

3.8.3 explicitly unmarked entry: An entry or a family member that is excluded from the SearchResult according

to a specification given in a control attribute referenced by the governing-search-rule.

3.8.4 family grouping: A set of members of a compound attribute that are grouped together for the purpose of

operation evaluation.

3.8.5 filter: An assertion about the presence or value of certain attributes of an entry in order to limit the scope of a

search.
3.8.6 originator: The user that originated an operation.

3.8.7 participating member: A family member that is either a contributing member or is a member of a family

grouping that as a whole matched a search filter.

3.8.8 Password expiration: The situation where a user password has reached the end of its validity period: the

account is locked and the user has to change the password before doing any other directory operation.

3.8.9 Password quality attributes: Attributes that specify how a password shall be constructed. Password quality

attributes include things like minimum length, mixture of characters (uppercase, lowercase, figures, punctuations, etc),

and avoidance of trivial passwords.

3.8.10 Password history: List of old passwords and the times they were inserted in the history.

3.8.11 primary search: The search that starts from baseObject as specified by the originator in the search request.

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ISO/IEC 9594-3:2020 (E)

3.8.12 relaxation: A progressive modification of the behaviour of a filter during a search operation so as to achieve

more matched entries if too few are received, or fewer matched entries if too many are received.

3.8.13 reply: A DAP/DSP result or an error; or an LDAP result.

3.8.14 request: Information consisting of an operation code and associated components to convey a directory operation

from a requester to a performer.

3.8.15 requester: A DUA, an LDAP client or a DSA sending a request to perform (i.e., invoke) an operation.

3.8.16 service controls: Parameters conveyed as part of an operation, which constrain various aspects of its

performance.

3.8.17 strand: A family grouping comprising all the members in a path from a leaf family member up to the ancestor

inclusive. A family member will reside in as many strands as there are leaf family members below it (as immediate or

non-immediate subordinates).
4 Abbreviations

For the purposes of this Recommendation | International Standard, the following abbreviations apply:

ACI Access Control Information
AVA Attribute Value Assertion
DIB Directory Information Base
DIT Directory Information Tree
DMD Directory Management Domain
DSA Directory System Agent
DUA Directory User Agent
LDAP Lightweight Directory Access Protocol
RDN Relative Distinguished Name
5 Conventions

The term "Directory Specification" (as in "this Directory Specification") shall be taken to mean Rec. ITU-T X.511 |

ISO/IEC 9594-3. The term "Directory Specifications" shall be taken to mean the Rec. ITU-T X.500 | ISO/IEC 9594-1,

Rec. ITU-T X.501 | ISO/IEC 9594-2, Rec. ITU-T X.511 | ISO/IEC 9594-3, Rec. ITU-T X.518 | ISO/IEC 9594-4, Rec.

ITU-T X.519 | ISO/IEC 9594-5, Rec. ITU-T X.520 | ISO/IEC 9594-6, Rec ITU-T X.521 | ISO/IEC 9594-7 and Rec. ITU-

T X.525 | ISO/IEC 9594-9.

If an International Standard or ITU-T Recommendation is referenced within normal text without an indication of the

edition, the edition shall be taken to be the latest one as specified in the normative references clause.

Prior to year 2020, the parts making up the Directory Specifications progressed together and can therefore collectively be

identified as the Directory Specifications of a specific edition using the format: Rec. ITU-T X.5** (yyyy) | ISO/IEC 9594-

*:yyyy (e.g.; Rec ITU-T X.5** (1993) | ISO/IEC 9594-*:1995).

This Directory Specification makes extensive use of Abstract Syntax Notation One (ASN.1) for the formal specification

of data types and values, as it is specified in Rec. ITU-T X.680 | ISO/IEC 8824-1, ITU-T X.681 (2015) | ISO/IEC 8824-

2, ITU-T X.682 (2015) | ISO/IEC 8824-3, ITU-T X.683 (2015) | ISO/IEC 8824-4 and Rec. ITU-T X.690 | ISO/IEC 8825-

This Direc
...

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