ISO 14533-3:2025

Processes, data elements and documents in commerce, industry and administration - Long-term signature - Part 3: Profiles for PDF Advanced Electronic Signatures (PAdES)

This document specifies the elements, among those defined in PDF digital signatures (PAdES), that enable verification of a digital signature over a long period of time. It does not give new technical specifications about the digital signature itself, nor new restrictions of usage of the technical specifications about the digital signatures which already exist.

Processus, éléments d'informations et documents dans le commerce, l'industrie et l'administration — Signature à long terme — Partie 3: Profils pour les signatures électroniques avancées des PDF (PAdES)

General Information

• Status: Published
• Publication Date: 20-Oct-2025
• ICS: 35.240.63 - IT applications in trade
• Technical Committee: ISO/TC 154 - Processes, data elements and documents in commerce, industry and administration
• Drafting Committee: ISO/TC 154/WG 6 - Trusted eCommunications
• Current Stage: 6060 - International Standard published
• Start Date: 21-Oct-2025
• Due Date: 03-Nov-2025
• Completion Date: 21-Oct-2025

Relations

• Revises: ISO 14533-3:2017 - Processes, data elements and documents in commerce, industry and administration - Long term signature profiles - Part 3: Long term signature profiles for PDF Advanced Electronic Signatures (PAdES)
• Effective Date: 04-Nov-2023

Overview

ISO 14533-3:2025 - "Processes, data elements and documents in commerce, industry and administration - Long-term signature - Part 3: Profiles for PDF Advanced Electronic Signatures (PAdES)" defines profiles and required elements that make PDF digital signatures verifiable over the long term. The standard focuses on PAdES-based mechanisms (as used with CAdES signatures in PDF defined by ISO 32000-2) to ensure signing time can be identified, illegal alterations are detectable, and interoperability is achieved. It does not change low‑level signature algorithms or add new signature technical specifications.

Key topics and requirements

• Profiles defined:
  • PAdES-T - profile for timestamping signatures (signature timestamp stored in a signature attribute or subsequent object such as a document timestamp).
  • PAdES-A - archival profile that protects long‑term availability and integrity of validation data and signature-related information.
• Element requirement levels: each profile element is classified as Mandatory (M), Optional (O), Conditional (C) or Prohibited (P); mandatory elements must be implemented; conditional elements require separate specifications.
• Conformity rules: Implementations must include all Mandatory elements and document handling of Conditional elements. First‑party conformity requires a supplier’s declaration of conformity (Annex A).
• Supporting structures and topics included in the document: document security store dictionary, Validation‑Related Information (VRI) dictionary, document timestamps, timestamp token structure (Annex C), profiles for timestamp‑only usage (PAdES‑DT/DTA - Annex B), and handling of multiple signatures.
• Normative reference: ISO 32000‑2 (PDF 2.0) for PDF and PAdES/CAdES usage.

Applications and practical value

• Ensures long‑term verifiability of electronically signed PDF documents for archiving, legal evidence, regulatory compliance, and enterprise document workflows.
• Enables software vendors to build interoperable PDF signing and validation tools that preserve signature validity over many years.
• Supports trust service providers, timestamp authorities, and certification authorities in delivering services that meet defined long‑term signature profiles.
• Assists auditors and records managers to assess and certify long‑term signature handling in document management systems.

Who should use this standard

• PDF signing and validation software developers (desktop, server, cloud)
• Trust service providers, time‑stamping authorities and certification authorities
• Records management and archiving professionals
• Legal, compliance and IT security teams implementing long‑term digital evidence procedures

Related standards

• ISO 32000‑2 (PDF 2.0) - referenced for PDF and PAdES/CAdES usage
• ISO 14533 series - related parts on long‑term signature concepts and processes

Keywords: ISO 14533-3:2025, PAdES, PAdES-T, PAdES-A, PDF Advanced Electronic Signatures, long-term signature, timestamp, digital signature verification, ISO 32000-2.

Standards Content (Sample)

International
Standard
ISO 14533-3
Second edition
Processes, data elements and
2025-10
documents in commerce, industry
and administration — Long-term
signature —
Part 3:
Profiles for PDF Advanced
Electronic Signatures (PAdES)
Processus, éléments d'informations et documents dans le commerce,
l'industrie et l'administration — Signature à long terme —
Partie 3: Profils pour les signatures électroniques avancées des
PDF (PAdES)
Reference number
© ISO 2025
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
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Requirements . 3
5.1 Conformity to PAdES-T .3
5.2 Conformity to PAdES-A .3
5.3 Conformity to PAdES-DT/DTA .3
5.4 Declaration of conformity .3
6 Long-term signature profiles . 3
6.1 Definition of PAdES profile and positioning .3
6.2 Representation of the required level .4
6.3 Standard for setting the required level .4
6.4 PAdES-T profile .5
6.4.1 General .5
6.4.2 PAdES using CAdES signatures profile .6
6.4.3 Timestamp of PAdES-T profile .9
6.5 PAdES-A profile .9
6.5.1 General .9
6.5.2 Structure of the PAdES-A profile .9
6.5.3 Document security store dictionary .10
6.5.4 Signature VRI dictionary .10
6.5.5 Document timestamp . .10
6.5.6 Updating PAdES-A .11
6.5.7 Validation data for signature and timestamp .11
6.6 Multiple signatures .11
6.6.1 General .11
6.6.2 Timestamp for multiple signatures . 12
Annex A (informative) Supplier's declaration of conformity and its attachment .13
Annex B (normative) The profile for using only timestamp .18
Annex C (normative) Structure of timestamp token .20
Annex D (informative) Applying PAdES using CMS signatures .22
Annex E (informative) Examples of multiple signatures .23
Bibliography .26

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
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 ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes 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 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. ISO 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
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 Technical Committee ISO/TC 154, Processes, data elements and documents in
commerce, industry and administration.
This second edition cancels and replaces the first edition (ISO 14533-3:2017), which has been technically
revised.
The main changes are as follows:
— terms and definitions have been added in the Clause 3 for clarity;
— the description and the title of tables have been changed in 6.4.2 for clarity.
A list of all parts in the ISO 14533 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.

iv
Introduction
The purpose of this document is to ensure the interoperability of implementations with respect to long-term
signatures that make electronic signatures verifiable in the long term. Long-term signature specifications
referenced by each implementation cover CAdES signatures as used in PDF described in ISO 32000-2
(PDF2.0).
v
International Standard ISO 14533-3:2025(en)
Processes, data elements and documents in commerce,
industry and administration — Long-term signature —
Part 3:
Profiles for PDF Advanced Electronic Signatures (PAdES)
1 Scope
This document specifies the elements, among those defined in PDF digital signatures (PAdES), that enable
verification of a digital signature over a long period of time.
It does not give new technical specifications about the digital signature itself, nor new restrictions of usage
of the technical specifications about the digital signatures which already exist.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 32000-2, Document management — Portable document format — Part 2: PDF 2.0
3 Terms and definitions
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
long-term signature
signature that is made verifiable having the ability to maintain its validity status and to get a proof of
existence of the associated signed data for a long term by implementing measures to enable the detection
of illegal alterations of signature information, including the identification of signing time, the subject of said
signature, and validation data
[SOURCE: ISO 14533-1:2022, 3.1]
3.2
profile
rule used to ensure interoperability, related to the optional elements of referenced specifications, the range
of values, etc.
3.3
required level
level of requirement for implementing each element constituting a profile (3.2)

3.4
trust anchor
origin of trust provided in the form of a public key certificate (3.7) or public key used by the validator to
validate an electronic signature, and generally a public key certificate issued by a trusted root certification
authority (3.6)
[SOURCE: ISO 14533-1:2022, 3.18]
3.5
trusted third party
TTP
security authority or its agent entrusted by another entity in connection with activities related to security
[SOURCE: ISO 14533-1:2022, 3.19]
3.6
certification authority
CA
centre that is entrusted with the development and assignment of public key certificates (3.7)
Note 1 to entry: Certification authorities can, at their discretion, develop and assign keys to entities.
3.7
certificate
information on the publicly disclosed key as a part of an asymmetric key pair for an entity, signed by a
certification authority to prevent forgery
3.8
PAdES
PAdES digital signature
CAdES signature as used in PDF for which the signer can be identified and any illegal data alteration detected
Note 1 to entry: PDF shall be as defined in ISO 32000-2.
3.9
PAdES-T
PAdES with time
CAdES signature as used in PDF with information to ascertain signing text of the definition
EXAMPLE Signature timestamp, document timestamp.
Note 1 to entry: PDF shall be as defined in ISO 32000-2.
3.10
PAdES-A
archival PAdES
CAdES signature as used in PDF with information that enables the detection of any illegal alterations of
information pertaining to the signature, including the subject of the signature and validation data
Note 1 to entry: PDF shall be as defined in ISO 32000-2.
4 Abbreviated terms
EOF end of file
VRI validation-related information

5 Requirements
5.1 Conformity to PAdES-T
The generation or validation of PAdES-T data conforms to this document, provided that the following
requirements are met:
a) all processing of elements whose required level is “Mandatory” in the PAdES-T profile as specified in
this document, shall be included;
b) detailed specifications pertaining to the processing of any element whose required level is “Conditional”
in the PAdES-T profile, as specified in this document, shall be provided.
5.2 Conformity to PAdES-A
The generation or validation of PAdES-A data conforms to this document provided that the following
requirements are met:
a) all processing of elements whose required level is “Mandatory” in the PAdES-A profile as specified in
this document, shall be included;
b) detailed specifications pertaining to the processing of any element whose required level is “Conditional”
in the PAdES-A profile as specified in this document, shall be provided.
5.3 Conformity to PAdES-DT/DTA
The generation or validation of PAdES-DT and PAdES-DTA data conforms to this document, provided that the
requirements of Figures B.1 and B.2 respectively are met. The profile shall be in accordance with Annex B.
5.4 Declaration of conformity
If first-party conformity assessment is used, the implementer shall make a declaration of conformity to this
document by disclosing the supplier's declaration of compliance and its attachment (see Annex A) containing
a description of implementation status (and the specifications for any elements “Conditional”).
NOTE 1 See ISO/IEC 17050-1.
NOTE 2 Figure 1 shows the positioning of the generation and validation of PAdES-T data and PAdES-A data.
6 Long-term signature profiles
6.1 Definition of PAdES profile and positioning
In order to make electronic signatures verifiable in the long term:
— signing time shall be identifiable;
— any illegal alterations of information pertaining to signatures, including the subject of information and
validation data, shall be detectable;
— interoperability shall be ensured.
To meet these requirements, this document defines the following two profiles with respect to PAdES.
a) PAdES-T profile: a profile pertaining to the generation and validation of the signature with a timestamp
for signature. The timestamp is stored in a signature timestamp attribute of the signature, or in any
subsequent object containing the timestamp, covering the signature. The subsequent object is a
document timestamp or a signature with the signature timestamp attribute.

b) PAdES-A profile: a profile pertaining to the generation and validation in the long-term availability and
integrity of the validation data that protects the PAdES-T data, including validation data from any illegal
alterations.
Figure 1 shows the relation between the PAdES-T data and the PAdES-A data.
Figure 1 — Relation between the PAdES-T data and the PAdES-A data
If only timestamps are attached to PDF data, PAdES-DT profile shall be applied in accordance with Annex B.
6.2 Representation of the required level
This document defines the following representation methods for the required level (as a profile) of each
element constituting PAdES-T data and PAdES-A data.
a) Mandatory (M) elements whose required level is “Mandatory” shall be implemented without fail. If such
an element has optional sub-elements, at least one sub-element shall be selected. Any element whose
required level is “Mandatory” and is one of the sub-elements of an optional element shall be selected
whenever the optional element is selected.
b) Optional (O) elements whose required level is “Optional” may be implemented at the discretion of the
implementer.
c) Conditional (C) elements whose required level is “Conditional” may be implemented at the discretion
of the implementer, provided that detailed specifications for the processing thereof are provided
separately.
d) Prohibited (P) elements whose required level is “Prohibited” shall not be created or modified, may be read.
6.3 Standard for setting the required level
The required level of each element constituting PAdES-T data and PAdES-A data shall be set in accordance
with the following requirements.
a) The required level shall be “Mandatory” for elements whose required level is “Mandatory” in the
definition of PAdES, and those necessary for the generation and validation of long-term signatures.
The elements whose required level is “Optional” in the definition of PAdES are defined as “Mandatory”,
“Optional” or “Conditional”.
b) The required level shall be “Conditional” for externally defined elements.
EXAMPLE 1 OtherCertificateFormat.

c) The required level shall be “Conditional” for elements intended to interact with a certain application.
EXAMPLE 2 CommitmentType.
d) The required level shall be “Conditional” for elements with an operation-dependent factor.
EXAMPLE 3 Attribute certificate; time mark.
NOTE The archiving-type timestamp defined in ISO/IEC 18014-2 is included in time mark or other method.
e) The required level shall be “optional” for elements only containing reference information.
6.4 PAdES-T profile
6.4.1 General
The PAdES-T profile is defined as the form of an electronic signature of which the signature value is protected
by any subsequent object containing trusted evidence as a proof of existence (e.g. document timestamp).
The PAdES-T is extended from the PAdES using CAdES signatures specified in 6.4.2. The required levels of
constituent elements of the PAdES using CAdES signatures are also specified in 6.4.2.
The following three types are defined as forms of the PAdES-T profile.
— PAdES-T by document timestamp
— PAdES-T by signature timestamp attribute
— PAdES-T by subsequent signature with signature timestamp attribute
These forms are shown in Figures 2 to 4.
The required levels of PAdES-T profile are specified in 6.4.3.
Figure 2 — PAdES-T profile by document timestamp

Figure 3 — PAdES-T profile by signature timestamp attribute
Figure 4 — PAdES-T profile by subsequent signature with signature timestamp attribute
6.4.2 PAdES using CAdES signatures profile
Table 1 specifies the required levels of entries that constitute the signature directory of the PAdES using
CAdES signatures profile. The element which has not been indicated is set to C (Conditional).
Table 1 — Signature dictionary of PAdES using CAdES signatures
Entry Required level Value
Type O Sig
Filter M
a
SubFilter M ETSI.CAdES.detached
Contents M See Table 2
ByteRange M
b
M M
Cert P
a
See also Annex D.
b
Even if a signature does not contain M entry, a signature validation application shall not consider this signature invalid. Time
of M entry is not basically used to validate certificates. If this information is used for validation, it is necessary to define clearly a
usage of this information (e.g. describing a usage in a signature policy).

TTaabblle 1 e 1 ((ccoonnttiinnueuedd))
Entry Required level Value
Location O
Reason O
ContactInfo O
a
See also Annex D.
b
Even if a signature does not contain M entry, a signature validation application shall not consider this signature invalid. Time
of M entry is not basically used to validate certificates. If this information is used for validation, it is necessary to define clearly a
usage of this information (e.g. describing a usage in a signature policy).
Table 2 specifies the required levels of elements that constitute the ContentInfo in the signature data.
Table 2 — Contents in signature (ContentInfo in CAdES structure)
Element Required level Value
ContentType M id-signedData
Content M See Table 3
Table 3 specifies the required levels of elements that constitute the Content element in the signature. And the
Content element has the meaning of SignedData. A DER-encoded SignedData object as specified in CMS shall
be included as the PDF signature in the entry with the key Content of the signature dictionary as described
in ISO 32000-2.
Table 3 — Content in signature (SignedData)
Element Required level
CMSVersion M
DigestAlgorithmIdentifiers M
EncapsulatedContentInfo M
—  eContentType M
—  eContent P
CertificateSet (Certificates) M
a
—  certificate M
—  v2AttrCert P
—  other C
RevocationInfoChoices (crls) O
—  crl O
—  other C
b
SignerInfos M
—  signerInfo M
a
At least a signature generation application shall contain a signer certificate for interoperability. Even if a signature does not
contain this element, a signature validation application shall not consider this signature invalid.
b
Only a single signerInfo shall be present in PDF signature.
Table 4 specifies the required levels of elements that constitute the SignerInfo in the signature data.

Table 4 — SignerInfo in signature
Element Required level
CMSVersion M
SignerIdentifier M
—  issuerAndSerialNumber O
—  subjectIdentifier O
DigestAlgorithmIdentifier M
SignedAttributes M
SignatureAlgorithmIdentifier M
SignatureValue M
UnsignedAttributes O
Table 5 specifies the required levels of elements that constitute the SignedAttributes. The element which has
not been indicated is set to C (Conditional).
Table 5 — SignedAttribute in signature
Element Required level
ContentType M
MessageDigest M
SigningCertificateReference M
—  ESS SigningCertificate O
a
—  ESS SigningCertificateV2 O
—  otherSigningCertificate C
b
SignaturePolicyIdentifier C
b
CommitmentType C
SignerIdentifier C
ContentTimestamp C
SigningTime P
ContentReference P
ContentIdentifier P
ContentHints P
c
SignerAttributes C
d
SignerLocation O
a
When a signature which complies with the PAdES using CAdES signatures is generated, the attribute of signingCertificateV2
shall be present in signedAttrs.
b
See ISO 32000-2:2020, 12.8.3.4.4.
c
See ISO 32000-2:2020, 12.8.3.4.3.
d
Either SignerLocation attribute or Location entry in Table 1 may be used.
Table 6 specifies the requ
...