ISO/IEC 9594-8:2020/Amd 1:2025

International
Standard
ISO/IEC 9594-8
Ninth edition
Information technology — Open
2020-11
systems interconnection —
AMENDMENT 1
Part 8:
2025-05
The Directory: Public-key and
attribute certificate frameworks
AMENDMENT 1: Miscellaneous
enhancements
Reference number
ISO/IEC 9594-8:2020/Amd. 1:2025(en) © ISO/IEC 2025

ISO/IEC 9594-8:2020/Amd. 1:2025(en)
© ISO/IEC 2025
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ISO/IEC 9594-8:2020/Amd. 1:2025(en)
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
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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.
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had
not received notice of (a) patent(s) which may be required to implement this document. However,
implementers are cautioned that this may not represent the latest information, which may be obtained
from the patent database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall
not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
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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. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by ITU-T as ITU-T X.509 (2019) Amd. 1 (10/2024) 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.
A list of all parts in the ISO/IEC 9594 series can be found on the ISO and IEC websites.
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 and
www.iec.ch/national-committees.
Rec. ITU-T X.509 (2019) Amd. 1 (10/2024)
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 9594-8:2020/Amd. 1:2025(en)
INTERNATIONAL STANDARD ISO/IEC 9594-8
RECOMMENDATION ITU-T X.509
Information technology – Open Systems Interconnection – The Directory: Public-key and
attribute certificate frameworks

Amendment 1
Miscellaneous enhancements
Summary
Recommendation ITU-T X.509 (2019) | International Standard ISO/IEC 9594-8:2020, Amendment 1 introduces text
updates to facilitate separation between cybersecurity ASN.1 modules and directory ASN.1 modules.

History
Edition Recommendation Approval Study Group Unique ID
1.0 ITU-T X.509 1988-11-25 11.1002/1000/2999
2.0 ITU-T X.509 1993-11-16 7 11.1002/1000/3000
3.0 ITU-T X.509 1997-08-09 7 11.1002/1000/4123
3.1   ITU-T X.509 (1997) Technical Cor. 1 2000-03-31 7 11.1002/1000/5033
3.2   ITU-T X.509 (1997) Technical Cor. 2 2001-02-02 7 11.1002/1000/5311
3.3   ITU-T X.509 (1997) Technical Cor. 3 2001-10-29 7 11.1002/1000/5559
3.4   ITU-T X.509 (1997) Technical Cor. 4 2002-04-13 17 11.1002/1000/6025
3.5   ITU-T X.509 (1997) Technical Cor. 5 2003-02-13 17 11.1002/1000/6236
3.6   ITU-T X.509 (1997) Technical Cor. 6 2004-04-29 17 11.1002/1000/7285
4.0 ITU-T X.509 2000-03-31 7 11.1002/1000/5034
4.1   ITU-T X.509 (2000) Technical Cor. 1 2001-10-29 7 11.1002/1000/5560
4.2   ITU-T X.509 (2000) Technical Cor. 2 2002-04-13 17 11.1002/1000/6026
4.3   ITU-T X.509 (2000) Technical Cor. 3 2003-02-13 17 11.1002/1000/15258
4.3   ITU-T X.509 (2000) Technical Cor. 3 2004-04-29 17 11.1002/1000/7284
4.4   ITU-T X.509 (2000) Technical Cor. 4 2007-01-13 17 11.1002/1000/8637
5.0 ITU-T X.509 2005-08-29 17 11.1002/1000/8501
5.1   ITU-T X.509 (2005) Cor. 1 2007-01-13 17 11.1002/1000/9051
5.2   ITU-T X.509 (2005) Cor. 2 2008-11-13 17 11.1002/1000/9591
5.3   ITU-T X.509 (2005) Cor. 3 2011-02-13 17 11.1002/1000/11042
5.4   ITU-T X.509 (2005) Cor. 4 2012-04-13 17 11.1002/1000/11577
6.0 ITU-T X.509 2008-11-13 17 11.1002/1000/9590
6.1   ITU-T X.509 (2008) Cor. 1 2011-02-13 17 11.1002/1000/11043
6.2   ITU-T X.509 (2008) Cor. 2 2012-04-13 17 11.1002/1000/11578
6.3   ITU-T X.509 (2008) Cor. 3 2012-10-14 17 11.1002/1000/11736
7.0 ITU-T X.509 2012-10-14 17 11.1002/1000/11735
7.1   ITU-T X.509 (2012) Cor. 1 2015-05-29 17 11.1002/1000/12474
7.2   ITU-T X.509 (2012) Cor. 2 2016-04-29 17 11.1002/1000/12844
7.3   ITU-T X.509 (2012) Cor. 3 2016-10-14 17 11.1002/1000/13032
8.0 ITU-T X.509 2016-10-14 17 11.1002/1000/13031
9.0 ITU-T X.509 2019-10-14 17 11.1002/1000/14033
9.1   ITU-T X.509 (2019) Cor. 1 2021-10-14 17 11.1002/1000/14791
9.2   ITU-T X.509 (2019) Cor. 2 2023-10-29 17 11.1002/1000/15705
9.3   ITU-T X.509 (2019) Amd. 1 2024-10-29 17 11.1002/1000/16172

To access the Recommendation, type the URL https://handle.itu.int/ in the address field of your web browser, followed by the
Recommendation's unique ID.
Rec. ITU-T X.509 (2019) Amd. 1 (10/2024)
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ISO/IEC 9594-8:2020/Amd. 1:2025(en)

FOREWORD
The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of
telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication
Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical,
operating and tariff questions and issuing Recommendations on them with a view to standardizing
telecommunications on a worldwide basis.
The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes
the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
In some areas of information technology which fall within ITU-T's purview, the necessary standards are
prepared on a collaborative basis with ISO and IEC.

NOTE
In this Recommendation, the expression "Administration" is used for conciseness to indicate both a
telecommunication administration and a recognized operating agency.
Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain
mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the
Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other
obligatory language such as "must" and the negative equivalents are used to express requirements. The use of
such words does not suggest that compliance with the Recommendation is required of any party.

INTELLECTUAL PROPERTY RIGHTS
ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve
the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or
applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of
the Recommendation development process.
As of the date of approval of this Recommendation, ITU had not received notice of intellectual property,
protected by patents/software copyrights, which may be required to implement this Recommendation.
However, implementers are cautioned that this may not represent the latest information and are therefore
strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at
https://www.itu.int/ITU-T/ipr/.

 ITU 2025
All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior
written permission of ITU.
Rec. ITU-T X.509 (2019) Amd. 1 (10/2024)
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 9594-8:2020/Amd. 1:2025(en)

CONTENTS
Page
1) Clause 13.2.13 . 1
2) Annex A, clause A.1 . 1
3) Annex A, clause A.2 . 2
4) Annex A, clause A.3 . 3
5) Annex B . 3
6) Annex C, clause C.2 . 4
7) Annex D . 5
Rec. ITU
...