ISO/IEC 9594-8:2020

Information technology — Open systems interconnection — Part 8: The Directory: Public-key and attribute certificate frameworks

This document addresses some of the security requirements in the areas of authentication and other security services through the provision of a set of frameworks upon which full services can be based. Specifically, this Recommendation | International Standard defines frameworks for: ? public-key certificates; and ? attribute certificates. The public-key certificate framework defined in this Recommendation | International Standard specifies the information objects and data types for a public-key infrastructure (PKI), including public-key certificates, certificate revocation lists (CRLs), trust broker and authorization and validation lists (AVLs). The attribute certificate framework specifies the information objects and data types for a privilege management infrastructure (PMI), including attribute certificates, and attribute certificate revocation lists (ACRLs). This Recommendation | International Standard also provides the framework for issuing, managing, using and revoking certificates. An extensibility mechanism is included in the defined formats for both certificate types and for all revocation list schemes. This Recommendation | International Standard also includes a set of extensions, which is expected to be generally useful across a number of applications of PKI and PMI. The schema components (including object classes, attribute types and matching rules) for storing PKI and PMI information in a directory, are included in this Recommendation | International Standard. This Recommendation | International Standard specifies the framework for strong authentication, involving credentials formed using cryptographic techniques. It is not intended to establish this as a general framework for authentication, but it can be of general use for applications which consider these techniques adequate. Authentication (and other security services) can only be provided within the context of a defined security policy. It is a matter for users of an application to define their own security policy.

Technologies de l'information — Interconnexion de systèmes ouverts (OSI) — Partie 8: Titre manque

General Information

• Status: Published
• Publication Date: 30-Nov-2020
• ICS: 35.100.70 - Application layer
• Technical Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Drafting Committee: ISO/IEC JTC 1/SC 6/WG 10 - Directory, ASN.1 and Registration
• Current Stage: 6060 - International Standard published
• Start Date: 30-Nov-2020
• Due Date: 19-Dec-2022
• Completion Date: 01-Dec-2020

Relations

• Revises: ISO/IEC 9594-8:2017 - Information technology — Open Systems Interconnection — The Directory — Part 8: Public-key and attribute certificate frameworks
• Effective Date: 23-Apr-2020

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 9594-8
Ninth edition
2020-11
Information technology — Open
systems interconnection —
Part 8:
The Directory: Public-key and
attribute certificate frameworks
Reference number
ISO/IEC 9594-8:2020(E)
©
ISO/IEC 2020

---------------------- Page: 1 ----------------------
ISO/IEC 9594-8:2020(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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC 9594-8:2020(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.509 (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 9594-8:2017), 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

---------------------- Page: 3 ----------------------
ISO/IEC 9594-8:2020 (E)
CONTENTS
Page
SECTION 1 – General . 1
1 Scope . 1
2 Normative references. 1
2.1 Identical Recommendations | International Standards . 1
2.2 Paired Recommendations | International Standards equivalent in technical content . 2
2.3 Recommendations . 2
2.4 Other references . 2
3 Definitions . 3
3.1 OSI Reference Model security architecture definitions. 3
3.2 Baseline identity management terms and definitions . 3
3.3 Directory model definitions . 3
3.4 Access control framework definitions . 3
3.5 Public-key and attribute certificate definitions . 3
4 Abbreviations . 7
5 Conventions . 8
6 Frameworks overview . 8
6.1 Digital signatures . 9
6.2 Public-key cryptography and cryptographic algorithms. 10
6.3 Distinguished encoding of basic encoding rules . 12
6.4 Applying distinguished encoding . 12
6.5 Using repositories . 13
SECTION 2 – PUBLIC-KEY CERTIFICATE FRAMEWORK . 14
7 Public keys and public-key certificates . 14
7.1 Introduction . 14
7.2 Public-key certificate. 14
7.3 Public-key certificate extensions . 17
7.4 Types of public-key certificates . 18
7.5 Trust anchor . 18
7.6 Entity relationship . 19
7.7 Certification path . 19
7.8 Generation of key pairs . 21
7.9 Public-key certificate creation . 21
7.10 Certificate revocation list . 22
7.11 Uniqueness of names . 25
7.12 Indirect CRLs . 25
7.13 Repudiation of a digital signing . 26
8 Trust models . 27
8.1 Three-cornered trust model . 27
8.2 Four cornered trust model . 27
9 Public-key certificate and CRL extensions . 28
9.1 Policy handling . 29
9.2 Key and policy information extensions . 31
9.3 Subject and issuer information extensions . 38
9.4 Certification path constraint extensions . 41
9.5 Basic CRL extensions . 45
9.6 CRL distribution points and delta CRL extensions . 52
9.7 Authorization and validation list extensions . 57
9.8 Alternative cryptographic algorithms and digital signature extensions . 58
10 Delta CRL relationship to base . 59
11 Authorization and validation lists . 60
11.1 Authorization and validation list concept . 60
© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.509 (10/2019) v

---------------------- Page: 4 ----------------------
ISO/IEC 9594-8:2020 (E)
Page
11.2 The authorizer . 60
11.3 Authorization and validation list syntax . 61
11.4 Multiple cryptographic algorithms for authorization and validation list . 62
12 Certification path processing procedure . 63
12.1 Path processing inputs . 63
12.2 Path processing outputs . 63
12.3 Path processing variables . 64
12.4 Initialization step . 64
12.5 Public-key certificate processing . 65
13 PKI directory schema . 67
13.1 PKI directory object classes and name forms . 67
13.2 PKI directory attributes . 68
13.3 PKI directory matching rules . 72
13.4 PKI directory syntax definitions. 77
SECTION 3 – ATTRIBUTE CERTIFICATE FRAMEWORK . 80
14 Attribute certificates . 80
14.1 General . 80
14.2 Attribute certificate syntax . 81
14.3 Multiple cryptographic algorithms for attribute certificates . 83
14.4 Delegation paths . 83
14.5 Attribute certificate revocation lists . 84
15 Attribute authority, source of authority and certification authority relationship . 86
15.1 Privilege in attribute certificates . 87
15.2 Privilege in public-key certificates . 87
16 PMI models . 87
16.1 General model . 87
16.2 Control model. 89
16.3 Delegation model . 90
16.4 Group assignment model . 90
16.5 Roles model . 91
16.6 Recognition of Authority Model . 93
16.7 XML privilege information attribute . 96
16.8 Permission attribute and matching rule . 97
17 Attribute certificate and attribute certificate revocation list extensions . 97
17.1 Basic privilege management extensions . 98
17.2 Privilege revocation extensions . 101
17.3 Source of authority extensions . 107
17.4 Role extensions . 109
17.5 Delegation extensions . 110
17.6 Recognition of authority extensions . 114
17.7 Use of alternative digital signature algorithm and digital signature extensions . 117
18 Delegation path processing procedure . 118
18.1 Basic processing procedure . 118
18.2 Role processing procedure . 119
18.3 Delegation processing procedure . 119
19 PMI directory schema. 121
19.1 PMI directory object classes . 121
19.2 PMI directory attributes . 123
19.3 PMI general directory matching rules . 125
Annex A – Public-key and attribute certificate frameworks . 127
Annex B – Reference definition of cryptographic algorithms . 155
Annex C Certificate extension attribute types . 162
© ISO/IEC 2020 – All rights reserved
vi Rec. ITU-T X.509 (10/2019)

---------------------- Page: 5 ----------------------
ISO/IEC 9594-8:2020 (E)
Page
C.1 Certificate extension attribute concept . 162
C.2 Formal specification for certificate extension attribute types . 162
Annex D – External ASN.1 modules . 171
Annex E – CRL generation and processing rules . 180
E.1 Introduction . 180
E.2 Determine parameters for CRLs . 181
E.3 Determine CRLs required . 182
E.4 Obtain CRLs. 183
E.5 Process CRLs . 183
Annex F – Examples of delta CRL issuance. 187
Annex G – Privilege policy and privilege attribute definition examples . 189
G.1 Introduction . 189
G.2 Sample syntaxes . 189
G.3 Privilege attribute example . 193
2)
Annex H – An introduction to public key cryptography . 194
Annex I – Examples of use of certification path constraints . 196
I.1 Example 1: Use of basic constraints . 196
I.2 Example 2: Use of policy mapping and policy constraints . 196
I.3 Use of name constraints extension . 196
Annex J – Guidance on determining for which policies a certification path is valid . 205
J.1 Certification path valid for a user-specified policy required . 205
J.2 Certification path valid for any policy required . 206
J.3 Certification path valid regardless of policy . 206
J.4 Certification path valid for a user-specific policy desired, but not required . 206
Annex K – Key usage certificate extension issues . 207
Annex L – Deprecated extensions . 208
L.1 CRL scope extension . 208
Annex M – Directory concepts . 211
M.1 Scope . 211
M.2 The directory attribute concept. 211
M.3 Basic directory concepts . 211
M.4 Subtrees . 212
M.5 Directory distinguished names . 212
M.6 Directory schema . 213
Annex N – Considerations on strong authentication . 214
N.1 Introduction . 214
N.2 One-way authentication . 215
N.3 Two-way authentication . 215
N.4 Three-way authentication . 216
N.5 Five-way authentication (initiated by A) . 217
N.6 Five-way authentication (initiated by B) . 218
Annex O – Alphabetical list of information item definitions . 220
Annex P – Amendments and corrigenda . 223
Bibliography . 224
© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.509 (10/2019) vii

---------------------- Page: 6 ----------------------
ISO/IEC 9594-8:2020 (E)
Introduction
Many applications have requirements for security to protect against threats to the communication of information. Virtually
all security services are dependent upon the identities of the communicating parties being reliably known, i.e.,
authenticated.
This Recommendation | International Standard defines a framework for public-key certificates. This framework includes
the specification of data objects used to represent the public-key certificates themselves, as well as revocation notices for
issued public-key certificates that should no longer be trusted. It defines some critical components of a public-key
infrastructure (PKI), but it does not define a PKI in its entirety. However, this Recommendation | International Standard
provides the foundation upon which full PKIs and their specifications can be built.
Similarly, this Recommendation | International Standard defines a framework for attribute certificates. This framework
includes the specification of data objects used to represent the attribute certificates themselves, as well as revocation
notices for issued attribute certificates that should no longer be trusted. It defines some critical components of a privilege
management infrastructure (PMI), but it does not define a PMI in its entirety. However, this Recommendation |
International Standard provides the foundation upon which full PMIs and their specifications can be built.
Directory schema definitions allow PKI and PMI information to be represented in a directory according to the
specification found in the Directory Specifications (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) or
according to the lightweight directory access protocol (LDAP) specification.
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, 2 and 3 of public-key certificates, versions 1 and 2 of certificate revocation lists
and version 2 of attribute certificates.
The extensibility function was added in an earlier edition with version 3 of the public-key certificate and with version 2
of the certificate revocation list and was incorporated into the attribute certificate from its initial inception.
Annex A, which is an integral part of this Recommendation | International Standard, provides the ASN.1 modules which
contain all of the definitions associated with the frameworks.
Annex B, which is not an integral part of this Recommendation | International Standard, lists object identifiers assigned
to cryptographic algorithms defined by other specifications. It is provided for easy reference and import into other ASN.1
modules.
Annex C, which is an integral part of this Recommendation | International Standard, provides definitions for how
certificate extension types may be represented by directory attribute types.
Annex D, which is not an integral part of this Recommendation | International Standard, includes extracts of external
ASN.1 modules referenced by this Recommen
...

INTERNATIONAL ISO/IEC
STANDARD 9594-8
Ninth edition
Information technology — Open
systems interconnection —
Part 8:
The Directory: Public-key and
attribute certificate frameworks
PROOF/ÉPREUVE
Reference number
ISO/IEC 9594-8:2020(E)
©
ISO/IEC 2020

---------------------- Page: 1 ----------------------
ISO/IEC 9594-8:2020(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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO/IEC 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC 9594-8:2020(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.509 (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 9594-8:2020 (E)
CONTENTS
Page
SECTION 1 – General . 1
1 Scope . 1
2 Normative references. 1
2.1 Identical Recommendations | International Standards . 1
2.2 Paired Recommendations | International Standards equivalent in technical content . 2
2.3 Recommendations . 2
2.4 Other references . 2
3 Definitions . 3
3.1 OSI Reference Model security architecture definitions. 3
3.2 Baseline identity management terms and definitions . 3
3.3 Directory model definitions . 3
3.4 Access control framework definitions . 3
3.5 Public-key and attribute certificate definitions . 3
4 Abbreviations . 7
5 Conventions . 8
6 Frameworks overview . 8
6.1 Digital signatures . 9
6.2 Public-key cryptography and cryptographic algorithms. 10
6.3 Distinguished encoding of basic encoding rules . 12
6.4 Applying distinguished encoding . 12
6.5 Using repositories . 13
SECTION 2 – PUBLIC-KEY CERTIFICATE FRAMEWORK . 14
7 Public keys and public-key certificates . 14
7.1 Introduction . 14
7.2 Public-key certificate. 14
7.3 Public-key certificate extensions . 17
7.4 Types of public-key certificates . 18
7.5 Trust anchor . 18
7.6 Entity relationship . 19
7.7 Certification path . 19
7.8 Generation of key pairs . 21
7.9 Public-key certificate creation . 21
7.10 Certificate revocation list . 22
7.11 Uniqueness of names . 25
7.12 Indirect CRLs . 25
7.13 Repudiation of a digital signing . 26
8 Trust models . 27
8.1 Three-cornered trust model . 27
8.2 Four cornered trust model . 27
9 Public-key certificate and CRL extensions . 28
9.1 Policy handling . 29
9.2 Key and policy information extensions . 31
9.3 Subject and issuer information extensions . 38
9.4 Certification path constraint extensions . 41
9.5 Basic CRL extensions . 45
9.6 CRL distribution points and delta CRL extensions . 52
9.7 Authorization and validation list extensions . 57
9.8 Alternative cryptographic algorithms and digital signature extensions . 58
10 Delta CRL relationship to base . 59
11 Authorization and validation lists . 60
11.1 Authorization and validation list concept . 60
© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.509 (10/2019) v

---------------------- Page: 4 ----------------------
ISO/IEC 9594-8:2020 (E)
Page
11.2 The authorizer . 60
11.3 Authorization and validation list syntax . 61
11.4 Multiple cryptographic algorithms for authorization and validation list . 62
12 Certification path processing procedure . 63
12.1 Path processing inputs . 63
12.2 Path processing outputs . 63
12.3 Path processing variables . 64
12.4 Initialization step . 64
12.5 Public-key certificate processing . 65
13 PKI directory schema . 67
13.1 PKI directory object classes and name forms . 67
13.2 PKI directory attributes . 68
13.3 PKI directory matching rules . 72
13.4 PKI directory syntax definitions. 77
SECTION 3 – ATTRIBUTE CERTIFICATE FRAMEWORK . 80
14 Attribute certificates . 80
14.1 General . 80
14.2 Attribute certificate syntax . 81
14.3 Multiple cryptographic algorithms for attribute certificates . 83
14.4 Delegation paths . 83
14.5 Attribute certificate revocation lists . 84
15 Attribute authority, source of authority and certification authority relationship . 86
15.1 Privilege in attribute certificates . 87
15.2 Privilege in public-key certificates . 87
16 PMI models . 87
16.1 General model . 87
16.2 Control model. 89
16.3 Delegation model . 90
16.4 Group assignment model . 90
16.5 Roles model . 91
16.6 Recognition of Authority Model . 93
16.7 XML privilege information attribute . 96
16.8 Permission attribute and matching rule . 97
17 Attribute certificate and attribute certificate revocation list extensions . 97
17.1 Basic privilege management extensions . 98
17.2 Privilege revocation extensions . 101
17.3 Source of authority extensions . 107
17.4 Role extensions . 109
17.5 Delegation extensions . 110
17.6 Recognition of authority extensions . 114
17.7 Use of alternative digital signature algorithm and digital signature extensions . 117
18 Delegation path processing procedure . 118
18.1 Basic processing procedure . 118
18.2 Role processing procedure . 119
18.3 Delegation processing procedure . 119
19 PMI directory schema. 121
19.1 PMI directory object classes . 121
19.2 PMI directory attributes . 123
19.3 PMI general directory matching rules . 125
Annex A – Public-key and attribute certificate frameworks . 127
Annex B – Reference definition of cryptographic algorithms . 155
Annex C Certificate extension attribute types . 162
© ISO/IEC 2020 – All rights reserved
vi Rec. ITU-T X.509 (10/2019)

---------------------- Page: 5 ----------------------
ISO/IEC 9594-8:2020 (E)
Page
C.1 Certificate extension attribute concept . 162
C.2 Formal specification for certificate extension attribute types . 162
Annex D – External ASN.1 modules . 171
Annex E – CRL generation and processing rules . 180
E.1 Introduction . 180
E.2 Determine parameters for CRLs . 181
E.3 Determine CRLs required . 182
E.4 Obtain CRLs. 183
E.5 Process CRLs . 183
Annex F – Examples of delta CRL issuance. 187
Annex G – Privilege policy and privilege attribute definition examples . 189
G.1 Introduction . 189
G.2 Sample syntaxes . 189
G.3 Privilege attribute example . 193
2)
Annex H – An introduction to public key cryptography . 194
Annex I – Examples of use of certification path constraints . 196
I.1 Example 1: Use of basic constraints . 196
I.2 Example 2: Use of policy mapping and policy constraints . 196
I.3 Use of name constraints extension . 196
Annex J – Guidance on determining for which policies a certification path is valid . 205
J.1 Certification path valid for a user-specified policy required . 205
J.2 Certification path valid for any policy required . 206
J.3 Certification path valid regardless of policy . 206
J.4 Certification path valid for a user-specific policy desired, but not required . 206
Annex K – Key usage certificate extension issues . 207
Annex L – Deprecated extensions . 208
L.1 CRL scope extension . 208
Annex M – Directory concepts . 211
M.1 Scope . 211
M.2 The directory attribute concept. 211
M.3 Basic directory concepts . 211
M.4 Subtrees . 212
M.5 Directory distinguished names . 212
M.6 Directory schema . 213
Annex N – Considerations on strong authentication . 214
N.1 Introduction . 214
N.2 One-way authentication . 215
N.3 Two-way authentication . 215
N.4 Three-way authentication . 216
N.5 Five-way authentication (initiated by A) . 217
N.6 Five-way authentication (initiated by B) . 218
Annex O – Alphabetical list of information item definitions . 220
Annex P – Amendments and corrigenda . 223
Bibliography . 224
© ISO/IEC 2020 – All rights reserved
Rec. ITU-T X.509 (10/2019) vii

---------------------- Page: 6 ----------------------
ISO/IEC 9594-8:2020 (E)
Introduction
Many applications have requirements for security to protect against threats to the communication of information. Virtually
all security services are dependent upon the identities of the communicating parties being reliably known, i.e.,
authenticated.
This Recommendation | International Standard defines a framework for public-key certificates. This framework includes
the specification of data objects used to represent the public-key certificates themselves, as well as revocation notices for
issued public-key certificates that should no longer be trusted. It defines some critical components of a public-key
infrastructure (PKI), but it does not define a PKI in its entirety. However, this Recommendation | International Standard
provides the foundation upon which full PKIs and their specifications can be built.
Similarly, this Recommendation | International Standard defines a framework for attribute certificates. This framework
includes the specification of data objects used to represent the attribute certificates themselves, as well as revocation
notices for issued attribute certificates that should no longer be trusted. It defines some critical components of a privilege
management infrastructure (PMI), but it does not define a PMI in its entirety. However, this Recommendation |
International Standard provides the foundation upon which full PMIs and their specifications can be built.
Directory schema definitions allow PKI and PMI information to be represented in a directory according to the
specification found in the Directory Specifications (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) or
according to the lightweight directory access protocol (LDAP) specification.
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, 2 and 3 of public-key certificates, versions 1 and 2 of certificate revocation lists
and version 2 of attribute certificates.
The extensibility function was added in an earlier edition with version 3 of the public-key certificate and with version 2
of the certificate revocation list and was incorporated into the attribute certificate from its initial inception.
Annex A, which is an integral part of this Recommendation | International Standard, provides the ASN.1 modules which
contain all of the definitions associated with the frameworks.
Annex B, which is not an integral part of this Recommendation | International Standard, lists object identifiers assigned
to cryptographic algorithms defined by other specifications. It is provided for easy reference and import into other ASN.1
modules.
Annex C, which is an integral part of this Recommendation | International Standard, provides definitions for how
certificate extension types may be represented by directory attribute types.
Annex D, which is not an integral part of this Recommendation | International Standard, includes extracts of external
ASN.1 modules referenced by this Recommendation | International Standard.
Annex E, which is an integral part of this Recommendation | Int
...