SIST EN 319 421 V1.1.1:2016
(Main)Electronic Signatures and Infrastructures (ESI) - Policy and Security Requirements for Trust Service Providers issuing Time-Stamps
Electronic Signatures and Infrastructures (ESI) - Policy and Security Requirements for Trust Service Providers issuing Time-Stamps
The present document specifies policy and security requirements relating to the operation and management practices of
TSPs issuing time-stamps.
These policy requirements are applicable to TSPs issuing time-stamps. Such time-stamps can be used in support of
digital signatures or for any application requiring to prove that a datum existed before a particular time.
The present document can be used by independent bodies as the basis for confirming that a TSP can be trusted for
issuing time-stamps.
The present document does not specify:
• protocols used to access the TSUs;
NOTE 1: A time-stamping protocol is defined in IETF RFC 3161 [i.2] including optional update in IETF
RFC 5816 [i.3] and profiled in ETSI EN 319 422 [5].
• how the requirements identified herein can be assessed by an independent body;
• requirements for information to be made available to such independent bodies;
• requirements on such independent bodies.
NOTE 2: See ETSI EN 319 403 [i.9].
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OPOMBA 1: Protokol za časovno žigosanje je določen v standardu IETF RFC 3161 [i.2], vključno z izbirno posodobitvijo v standardu IETF RFC 5816 [i.3] in profilom v standardu ETSI EN 319 422 [5].
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General Information
Standards Content (Sample)
Draft ETSI EN 319 421 V1.0.0 (2015-06)
EUROPEAN STANDARD
Electronic Signatures and Infrastructures (ESI);
Policy and Security Requirements for
Trust Service Providers issuing Time-Stamps
�
2 Draft ETSI EN 319 421 V1.0.0 (2015-06)
Reference
DEN/ESI-0019421
Keywords
e-commerce, electronic signature, security,
time-stamping, trust services
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3 Draft ETSI EN 319 421 V1.0.0 (2015-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 9
4 General concepts . 10
4.1 General policy requirements concepts . 10
4.2 Time-stamping services . 10
4.3 Time-Stamping Authority (TSA) . 10
4.4 Subscriber . 10
4.5 Time-stamp policy and TSA practice statement . 11
5 Introduction to time-stamp policies and general requirements . 11
5.1 General . 11
5.2 Identification . 11
5.3 User community and applicability . 11
5.3.1 Best practices time-stamp policy . 11
6 Policies and practices . 12
6.1 Risk assessment . 12
6.2 Trust Service Practice Statement . 12
6.3 Terms and conditions . 12
6.4 Information security policy . 12
6.5 TSA obligations . 12
6.5.1 General . 12
6.5.2 TSA obligations towards subscribers . 12
6.6 Information for relying parties . 13
7 TSA management and operation . 13
7.1 Introduction . 13
7.2 Internal organization. 13
7.3 Personnel security. 13
7.4 Asset management . 13
7.5 Access control . 14
7.6 Cryptographic controls . 14
7.6.1 General . 14
7.6.2 TSU key generation . 14
7.6.3 TSU private key protection . 14
7.6.4 TSU public key certificate . 15
7.6.5 Rekeying TSU's key . 15
7.6.6 Life cycle management of signing cryptographic hardware . 15
7.6.7 End of TSU key life cycle . 15
7.7 Time-stamping . 16
7.7.1 Time-stamp issuance. 16
7.7.2 Clock synchronization with UTC . 16
7.8 Physical and environmental security . 17
7.9 Operation security . 17
7.10 Network security . 18
7.11 Incident management . 18
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7.12 Collection of evidence . 18
7.13 Business continuity management . 18
7.14 TSA termination and termination plans . 18
7.15 Compliance. 19
8 Additional requirements for Regulation (EU) No 910/2014 . 19
8.1 TSU public key certificate . 19
Annex A (informative): Potential liability in the provision of time-stamping services . 20
Annex B (informative): Model TSA disclosure statement . 21
B.1 Introduction . 21
B.2 TSA disclosure statement structure . 22
Annex C (informative): Coordinated Universal Time (UTC). 23
Annex D (informative): Long term verification of time-stamps . 24
Annex E (informative): Regulation (EU) No 910/2014 and qualified electronic time-stamp
policy cross-reference . 25
Annex F (informative): Possible implementation architectures - time-stamping service . 26
F.1 Managed time-stamping service . 26
F.2 Selective alternative quality . 26
Annex G (informative): Major changes from ETSI TS 102 023 . 28
Annex H (informative): Conformity Assessment Check list . 29
History . 30
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5 Draft ETSI EN 319 421 V1.0.0 (2015-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This draft European Standard (EN) has been produced by ETSI Technical Committee Electronic Signatures and
Infrastructures (ESI), and is now submitted for the combined Public Enquiry and Vote phase of the ETSI standards EN
Approval Procedure.
The present document was previously published as ETSI TS 102 023 [i.8].
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 12 months after doa
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The present document is aiming to meet the general requirements of the international community to provide trust and
confidence in electronic transactions including, amongst others, applicable requirements from Regulation (EU)
No 910/2014 [i.4].
The Regulation includes requirements for Trust Service Providers (TSP) providing services to the public, including
TSPs issuing time-stamps. Additionally, more specific requirements are identified in the Regulation for a specific class
of TSP called a Qualified TSP, with further specific requirements for those Qualified TSPs which issue qualified
time-stamps. The present document is aimed to meet the requirements of the Regulation for both Qualified and
non-Qualified TSPs issuing Qualified and non-Qualified electronic time-stamps respectively.
In order to verify an electronic signature, it can be necessary to prove that the signature from the signer was applied
when the signer's certificate was valid. This is necessary in two circumstances:
1) during the validity period of the signer's certificate, should the signer's certificate be revoked before the end of
its validity, e.g. because the signer's private key has been compromised;
2) after the end of the validity period of the signer's certificate, since CAs are not mandated to process revocation
status information beyond the end of the validity period of the certificates they have issued.
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6 Draft ETSI EN 319 421 V1.0.0 (2015-06)
One method consists to use a time-stamp which allows proving that a datum existed before a particular time. This
technique allows proving that the signature was generated before the date contained in the time-stamp. Policy
requirements to cover that case are the primary aim of the present document.
However, these policy requirements allow addressing other needs.
Time-stamping is gaining an increasing interest by the business sector and is becoming an important component of
digital signatures, this is commonly based upon the Time-Stamp protocol from the IETF RFC 3161 [i.2] which is
profiled in ETSI EN 319 422 [5]. Agreed minimum security and quality requirements are necessary in order to ensure
trustworthy validation of long-term digital signatures.
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7 Draft ETSI EN 319 421 V1.0.0 (2015-06)
1 Scope
The present document specifies policy and security requirements relating to the operation and management practices of
TSPs issuing time-stamps.
These policy requirements are applicable to TSPs issuing time-stamps. Such time-stamps can be used in support of
digital signatures or for any application requiring to prove that a datum existed before a particular time.
The present document can be used by independent bodies as the basis for confirming that a TSP can be trusted for
issuing time-stamps.
The present document does not specify:
• protocols used to access the TSUs;
NOTE 1: A time-stamping protocol is defined in IETF RFC 3161 [i.2] including optional update in
IETF RFC 5816 [i.3] and profiled in ETSI EN 319 422 [5].
• how the requirements identified herein can be assessed by an independent body;
• requirements for information to be made available to such independent bodies;
• requirements on such independent bodies.
NOTE 2: See ETSI EN 319 403 [i.10].
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.Not applicable.
[1] Recommendation ITU-R TF.460-6 (2002): "Standard-frequency and time-signal emissions".
[2] ISO/IEC 19790:2006: "Information technology -- Security techniques -- Security requirements for
cryptographic modules".
[3] ISO/IEC 15408 (1999) (parts 1 to 3): "Information technology -- Security techniques -- Evaluation
criteria for IT security".
[4] ETSI EN 319 401: "Electronic Signatures and Infrastructures (ESI); General Policy Requirements
for Trust Service Providers".
[5] ETSI EN 319 422: "Electronic Signatures and Infrastructures (ESI); Time-stamping protocol and
time-stamp profiles".
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2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 319 122: "Electronic Signatures and Infrastructures (ESI); CAdES digital signatures;
Part 1: Building blocks and CAdES baseline signatures".
[i.2] IETF RFC 3161 (2001): "Internet X.509 Public Key Infrastructure: Time-Stamp Protocol (TSP)".
[i.3] IETF RFC 5816: "ESSCertIDV2 update to RFC 3161".
[i.4] Regulation (EU) No 910/2014 of the European Parliament and of the Council on electronic
identification and trust services for electronic transactions in the internal market and repealing
Directive 1999/93/EC.
[i.5] Council Directive 93/13/EEC of 5 April 1993 on unfair terms in consumer contracts.
[i.6] BIPM Circular T.
NOTE: Available from the BIPM website http://www.bipm.org/.
[i.7] ETSI TS 119 312: "Electronic Signatures and Infrastructures (ESI); Cryptographic Suites".
[i.8] ETSI TS 102 023: "Electronic Signatures and Infrastructures (ESI); Policy requirements for time-
stamping authorities".
[i.9] FIPS PUB 140-2 (2001): "Security Requirements for Cryptographic Modules".
[i.10] ETSI EN 319 403: "Electronic Signatures and Infrastructures (ESI); Trust Service Provider
Conformity Assessment - Requirements for conformity assessment bodies assessing Trust Service
Providers".
[i.11] ETSI EN 319 411-1: "Electronic Signatures and Infrastructures (ESI); Policy and security
requirements for Trust Service Providers issuing certificates; Part 1: General requirements".
[i.12] ETSI EN 319 411-2: "Electronic Signatures and Infrastructures (ESI); Policy and security
requirements for Trust Service Providers issuing certificates; Part 2: Requirements for trust service
providers issuing EU qualified certificates".
[i.13] CEN EN 419 231: "Protection profile for trustworthy systems supporting time stamping".
[i.14] CEN EN 419 221-2: "Protection profiles for TSP Cryptographic modules - Part 2: Cryptographic
module for CSP signing operations with backup ".
[i.15] CEN EN 419 221-3: "Protection profiles for TSP Cryptographic modules - Part 3: Cryptographic
module for Cryptographic module for CSP key generation services ".
[i.16] CEN EN 419 221-4: "Protection profiles for TSP Cryptographic modules - Part 4: Cryptographic
module for CSP signing operations without backup".
[i.17] CEN EN 419 221-5: "Protection profiles for TSP Cryptographic modules - Part 5: Cryptographic
module for trust services".
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3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given ETSI EN 319 401 [4] and the following
apply:
NOTE: Where a definition is copied from a referenced document this is indicated by inclusion of the reference
identifier number at the end of the definition.
Coordinated Universal Time (UTC): time scale based on the second as defined in Recommendation ITU-R
TF.460-6 [1]
NOTE: For most practical purposes UTC is equivalent to mean solar time at the prime meridian (0°). More
specifically, UTC is a compromise between the highly stable atomic time (Temps Atomique International
- TAI) and solar time derived from the irregular Earth rotation (related to the Greenwich mean sidereal
time (GMST) by a conventional relationship) (see annex C for more details).
relying party: recipient of a time-stamp who relies on that time-stamp
subscriber: legal or natural person to whom a time-stamp is issued and who is bound to any subscriber obligations
time-stamp: data in electronic form which binds other electronic data to a particular time establishing evidence that
these data existed at that time
time-stamp policy: named set of rules that indicates the applicability of a time-stamp to a particular community and/or
class of application with common security requirements
NOTE: This is a specific type of trust service policy as defined in ETSI EN 319 401 [4].
trust service: electronic service that enhances trust and confidence in electronic transactions
Trust Service Provider (TSP): entity which provides one or more trust services
Time-Stamping Authority (TSA): TSP which issues time-stamps using one or more time-stamping units
Time-Stamping Unit (TSU): set of hardware and software which is managed as a unit and has a single time-stamp
signing key active at a time
TSA Disclosure statement: set of statements about the policies and practices of a TSA that particularly require
emphasis or disclosure to subscribers and relying parties, for example to meet regulatory requirements
TSA practice statement: statement of the practices that a TSA employs in issuing time-stamp
NOTE: This is a specific type of trust service practice statement as defined in ETSI EN 319 401 [4].
TSA system: composition of IT products and components organized to support the provision of time-stamping services
UTC(k): time scale realized by the laboratory "k" and kept in close agreement with UTC, with the goal to reach
±100 ns.
NOTE: A list of UTC(k) laboratories is given in clause 1 of Circular T [i.6] disseminated by BIPM and available
from the BIPM website (http://www.bipm.org/).
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in ETSI EN 319 401 [4] and the following apply:
BIPM Bureau International des Poids et Mesures
BTSP Best practices Time-Stamp Policy
CA Certification Authority
GMT Greenwich Mean Time
IERS International Earth Rotation and Reference System Service
IT Information Technology
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TAI International Atomic Time
TSA Time-Stamping Authority
TSP Trust Service Providers
TSU Time-Stamping Unit
UTC Coordinated Universal Time
4 General concepts
4.1 General policy requirements concepts
The present document references ETSI EN 319 401 [4] for generic policy requirements common to all classes of trust
service providers service.
These policy requirements are based upon the use of public key cryptography, public key certificates and reliable time
sources.
Subscriber and relying parties are expected to consult the TSA's practice statement to obtain further details of precisely
how this time-stamp policy is implemented by the particular TSA (e.g. protocols used in providing this service).
4.2 Time-stamping services
The provision of time-stamping services is broken down in the present document into the following component services
for the purposes of classifying requirements:
• Time-stamping provision: This service component generates time-stamps.
• Time-stamping management: This service component monitors and controls the operation of the
time-stamping services to ensure that the service provided is as specified by the TSA. This service component
has responsibility for the installation and de-installation of the time-stamping provision service.
EXAMPLE: Time-stamping management ensures that the clock used for time-stamping is correctly
synchronized with UTC.
This subdivision of services is only for the purposes of clarifying the requirements specified in the present document
and places no restrictions on any subdivision of an implementation of time-stamping services.
4.3 Time-Stamping Authority (TSA)
A Trust Service Provider (TSP) providing time-stamping services to the public, is called the Time-Stamping Authority
(TSA). The TSA has overall responsibility for the provision of the time-stamping services identified in clause 4.2. The
TSA has responsibility for the operation of one or more TSUs which creates and signs on behalf of the TSA. The TSA
responsible for issuing a time-stamp is identifiable (see clause 7.7.1, d).
The TSA may make use of other parties to provide parts of the time-stamping services. However, the TSA always
maintains overall responsibility (as per clause 6.5) and ensures that the policy requirements identified in the present
document are met.
EXAMPLE: A TSA sub-contracts all the component services, including the services which generate time-
stamps using the TSU's keys. However, the private key or keys used to generate the time-stamps
are identified as belonging to the TSA which maintains overall responsibility for meeting the
requirements defined in the present document.
A TSA may operate several identifiable time-stamping units.
A TSA is a trust service provider as described in ETSI EN 319 401 [4] which issues time-stamps.
4.4 Subscriber
When the subscriber is an organization, it comprises several end-users or an individual end-user and some of the
obligations that apply to that organization will have to apply as well to the end-users. In any case the organization will
be held responsible if the obligations from the end-users are not correctly fulfilled and therefore such an organization is
expected to suitably inform its end users.
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When the subscriber is an end-user, the end-user will be held directly responsible if its obligations are not correctly
fulfilled.
4.5 Time-stamp policy and TSA practice statement
This clause explains the relative roles of time-stamp policy and TSA practice statement. It places no restriction on the
form of a time-stamp policy or practice statement specification.
A time-stamp policy is a form of Trust Service Policy as specified in ETSI EN 319 401 [4] applicable to trust service
providers issuing time-stamps.
TSA Practice Statement is a form of Trust Service Practice Statement as specified in ETSI EN 319 401 [4] applicable to
trust service providers issuing time-stamps.
The present document specifies a time-stamp policy to meet general requirements for trusted time-stamping services.
TSAs specify in TSA practice statements how these requirements are met.
5 Introduction to time-stamp policies and general
requirements
5.1 General
The policy requirements are defined in the present document in terms of a time-stamp policy. The present document
specifies one time-stamp policy: a best practices time-stamp policy (BTSP) for TSAs issuing time-stamps, supported by
public key certificates, with an accuracy of 1 second or better.
A TSA may define its own policy which enhances a policy defined in the present document. Such a policy shall
incorporate or further constrain the requirements identified in the present document.
If an accuracy of better than 1 second is provided by the TSA then the accuracy shall be indicated in the TSA's
disclosure statement (see clause 6.3) and in each time-stamp issued to an accuracy of better than 1 second.
5.2 Identification
The identifier of the time-stamp policy specified in the present document is:
a) BTSP : a best practices policy for time-stamp.
itu-t(0) identified-organization(4) etsi(0)
time-stamp-policy(2023)
policy-identifiers(1) baseline-ts-policy (1)
By including this object identifier in a time-stamp, the TSA claims conformance to the identified time-stamp policy.
A TSA shall include the identifier for the time-stamp policy being supported in the TSA disclosure statement made
available to subscribers and relying parties to indicate its claim of conformance.
When the TSA uses its own identifier for the time-stamp policy, the TSA shall indicate in its policy document and in its
TSA disclosure statement, the ETSI time-stamping identifier (i.e. BSTP) being supported.
5.3 User community and applicability
5.3.1 Best practices time-stamp policy
This policy is aimed at meeting the requirements of time-stamp for long term validity (e.g. as defined in
ETSI EN 319 122 [i.1]) but is generally applicable to any use which has a requirement for equivalent quality.
This policy may be used for public time-stamping services or time-stamping services used within a closed community.
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6 Policies and practices
6.1 Risk assessment
The requirements identified in ETSI EN 319 401 [4], clause 5 shall apply.
6.2 Trust Service Practice Statement
The requirements identified in ETSI EN 319 401 [4], clause 6.1 shall apply.
In addition, the statement shall at least specify for each time-stamp policy supported by the TSA:
a) at least one hashing algorithm used to represent the datum being time-stamped;
b) the accuracy of the time in the time-stamps with respect to UTC;
c) any limitations on the use of the time-stamping service;
d) the subscriber's obligations as defined in clause 6.5.2, if any;
e) the relying party's obligations as defined in clause 6.6;
f) information on how to verify the time-stamp such that the relying party is considered to "reasonably rely" on
the time-stamp (see clause 6.6) and any possible limitations on the validity period; and
g) any claim to meet the requirements on time-stamping services under national law.
The TSA should include in its time-stamping disclosure statement availability of its service.
EXAMPLE: Expected mean time between failure of the time-stamping service, expected mean time to recovery
following a failure and provisions made for disaster recovery including back-up services.
The model TSA disclosure statement given in annex B may be used. Alternatively this may be provided as part of a
subscriber / relying party agreement.
The TSA disclosure statement may be included in a TSA practice statement provided that it is conspicuous to the
reader.
6.3 Terms and conditions
The general obligations specified in ETSI EN 319 401 [4], clause 6.2 shall apply.
6.4 Information security policy
The requirements identified in ETSI EN 319 401 [4], clause 6.3 shall apply.
6.5 TSA obligations
6.5.1 General
The TSA shall adhere to any additional obligations indicated in the time-stamp either directly or incorporated by
reference.
6.5.2 TSA obligations towards subscribers
The present document places no specific obligations on the subscriber beyond any TSA specific requirements stated in
the TSA's terms and conditions.
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6.6 Information for relying parties
The terms and conditions made available to relying parties (see clause 6.3) shall include an obligation on the relying
party, when relying on a time-stamp, to:
a) verify that the time-stamp has been correctly signed and that the private key used to sign the time-stamp has
not been compromised until the time of the verification;
NOTE: During the TSU's certificate validity period, the validity of the signing key can be checked using current
revocation status for the TSU's certificate. If the time of verification exceeds the end of the validity period
of the corresponding certificate, see annex D for guidance.
b) take into account any limitations on the usage of the time-stamp indicated by the time-stamp policy; and
c) take into account any other precautions prescribed in agreements or elsewhere.
7 TSA management and operation
7.1 Introduction
These policy requirements are not meant to imply any restrictions on charging for TSA services.
The requirements are indicated in terms of the security objectives followed by more specific requirements for controls
to meet those objectives where considered necessary to provide the necessary confidence that those objective will be
met.
NOTE: The details of controls required to meet an objective is a balance between achieving the necessary
confidence whilst minimizing the restrictions on the techniques that a TSA can employ in issuing
time-stamps. In ETSI EN 319 401 [4], reference is made to other more general standards which can be
used as a source of more detailed control requirements. Due to these factors the specificity of the
requirements given under a given topic can vary.
The provision of a time-stamp in response to a request is at the discretion of the TSA depending on any service level
agreements with the subscriber.
7.2 Internal organization
The requirements identified in ETSI EN 319 401 [4], clause 7.1 shall apply. In addition the following particular
requirements apply:
a) The TSA shall be a legal entity according to national law.
b) The TSA shall have a system or systems for quality and information security management appropriate for the
time-stamping services it is providing.
c) It shall employ a sufficient number of personnel having the necessary education, training, technical knowledge
and experience relating to the type, range and volume of work necessary to provide time-stamping services.
NOTE: Personnel employed by a TSA include individual personnel contractually engaged in performing
functions in support of the TSA's time-stamping services. Personnel who are involved only in monitoring
the TSA services need not be TSA personnel.
7.3 Personnel security
The requirements identified in ETSI EN 319 401 [4], clause 7.2 shall apply.
7.4 Asset management
The requirements identified in ETSI EN 319 401 [4], clause 7.3 shall apply.
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14 Draft ETSI EN 319 421 V1.0.0 (2015-06)
7.5 Access control
The requirements identified in ETSI EN 319 401 [4], clause 7.4 shall apply.
7.6 Cryptographic controls
7.6.1 General
The requirements identified in ETSI EN 319 401 [4], clause 7.5 shall apply.
7.6.2 TSU key generation
The following particular requirements apply:
a) The generation of the TSU's signing key(s) shall be undertaken in a physically secured environment (as per
clause 7.8) by personnel in trusted roles (as per clause 7.3) under, at least, dual control. The personnel
authorized to carry out this function shall be limited to those required to do so under the TSA's practices.
b) The generation of the TSU's signing key(s) shall be carried out within a cryptographic module(s) which either:
- meets the requirements identified in ISO/IEC 19790 [2], level 3 or higher; or
NOTE 1: Demonstrated conformance to FIPS PUB 140-2 [i.9], level 3 is considered as fulfillment of this
requirement.
- is a trustworthy system which is assured to EAL 4 or higher in accordance to ISO/IEC 15408 [3]; or
equivalent security criteria. This shall be to a security target or protection profile which meets the
requirements of the present document, based on a risk analysis and taking into account physical and other
non-technical security measures.
NOTE 2: Standards specifying common criteria protection profiles for TSP cryptographic modules, in accordance
with ISO 15408 [3], are currently under development within CEN as CEN EN 419 221-2 [i.14] or
CEN EN 419 221-3 [i.15], CEN EN 419 221-4 [i.16],or CEN EN 419 221-5 [i.17].
c) The TSU key generation algorithm, the resulting signing key length and signature algorithm used for signing
time-stamps key shall be recognized by any national supervisory body, or in accordance with existing current
state of art, as being fit for the purposes of time-stamps as issued by the TSA.
NOTE 3: See ETSI TS 119 312 [i.7] for guidance on signature algorithms and their parameters.
d) A TSU's signing key should not be imported into different cryptographic modules.
7.6.3 TSU private key protection
The TSU private keys shall remain confidential and their integrity shall be maintained with at least the following
particular requirements:
a) The TSU private signing key shall be held and used within a cryptographic module which:
- meets the requirements identified in ISO/IEC 19790 [2], level 3 or higher; or
NOTE 1: Demonstrated conformance to FIPS PUB 140-2 [i.9], level 3 is considered as fulfillment of this
requirement.
- is a trustworthy system which is assured to EAL 4 or higher in accordance to ISO/IEC 15408 [3], or
equivalent security criteria. This shall be to a security target or protection profile which meets the
requirements of the present document, based on a risk analysis and taking into account physical and other
non-technical security measures.
NOTE 2: Standards specifying common criteria protection profiles for TSP cryptographic modules, in accordance
with ISO 15408 [3], are currently under development within CEN as CEN EN 419 221-2 [i.14] or
CEN EN 419 221-3 [i.15], CEN EN 419 221-4 [i.16],or CEN EN 419 221-5 [i.17].
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15 Draft ETSI EN 319 421 V1.0.0 (2015-06)
b) If TSU private keys are backed up, they shall be copied, stored and recovered only by personnel in trusted
roles using, at least, dual control in a physically secured environment (see clause 7.8). The personnel
authorized to carry out this function shall be limited to those required to do so under the TSA's practices.
c) Any backup copies of the TSU private signing keys shall be protected to ensure its integrity and confidentiality
by the cryptographic module before being stored outside that device.
NOTE 3: Additional requirement for private key protection may be defined in the future following on the
agreement of a time-stamping protection profile to be CEN EN 419 231 [i.13].
7.6.4 TSU public key certificate
The TSA shall guarantee the integrity and authenticity of the TSU signature verification (public) keys with at least the
following particular requirements:
a) TSU signature verification (public) keys shall be made available to relying parties in a public key certificate.
b) The TSU signature verification (public) key certificate should be issued by a certification authority operating
under ETSI EN 319 411-1 [i.11].
c) The TSU shall not issue time-stamp before its signature verification (public key) certificate is loaded into the
TSU or its cryptographic device.
When obtaining a signature verification (public key) certificate, the TSA should verify that this certificate has been
correctly signed (including verification of the certificate chain to a trusted certification authority).
7.6.5 Rekeying TSU's key
The life-time of TSU's certificate shall not be longer than the period of time that the chosen algorithm and key length is
recognized as being fit for purpose (see clause 7.6.1c).
NOTE 1: The following additional considerations apply when limiting that lifetime:
• Clause 7.14 requires that records concerning time-stamping services be held for a period of time as appropriate
for at least 1 year after the expiration of the validity of the TSU's signing keys. The longer the validity period
of the TSU certificates will be, the longer the size of the records to be kept will be.
• Should a TSU private key or certificate be compromised, the older the TSU certificate the more time-stamps
will be affected.
NOTE 2: TSU key compromise does not only depend on the characteristics of the cryptographic module being used
but also on the procedures being used at system initialization and key export (when that function is
supported).
7.6.6 Life cycle management of signing cryptographic hardware
The following particular requirements apply:
a) Time-stamp signing cryptographic hardware shall not be tampered with during shipment.
b) Time-stamp signing cryptographic hardware shall not be tampered with when and while stored.
c) Installation, activation and duplication of TSU's signing keys in cryptographic hardware shall be done only by
personnel in trusted roles using, at least, dual control in a physically secured environment (see clause 7.8).
d) TSU private signing keys stored on TSU cryptographic module shall be erased upon device retirement in a
way that it is practically impossible to recover them.
7.6.7 End of TSU key life cycle
The TSA shall define
...
EUROPEAN STANDARD
Electronic Signatures and Infrastructures (ESI);
Policy and Security Requirements for
Trust Service Providers issuing Time-Stamps
�
2 ETSI EN 319 421 V1.1.1 (2016-03)
Reference
DEN/ESI-0019421
Keywords
e-commerce, electronic signature, security,
time-stamping, trust services
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3 ETSI EN 319 421 V1.1.1 (2016-03)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 9
4 General concepts . 10
4.1 General policy requirements concepts . 10
4.2 Time-stamping services . 10
4.3 Time-Stamping Authority (TSA) . 10
4.4 Subscriber . 11
4.5 Time-stamp policy and TSA practice statement . 11
5 Introduction to time-stamp policies and general requirements . 11
5.1 General . 11
5.2 Identification . 11
5.3 User community and applicability . 12
5.3.1 Best practices time-stamp policy . 12
6 Policies and practices . 12
6.1 Risk assessment . 12
6.2 Trust Service Practice Statement . 12
6.3 Terms and conditions . 12
6.4 Information security policy . 12
6.5 TSA obligations . 12
6.5.1 General . 12
6.5.2 TSA obligations towards subscribers . 13
6.6 Information for relying parties . 13
7 TSA management and operation . 13
7.1 Introduction . 13
7.2 Internal organization. 13
7.3 Personnel security. 13
7.4 Asset management . 14
7.5 Access control . 14
7.6 Cryptographic controls . 14
7.6.1 General . 14
7.6.2 TSU key generation . 14
7.6.3 TSU private key protection . 15
7.6.4 TSU public key certificate . 15
7.6.5 Rekeying TSU's key . 15
7.6.6 Life cycle management of signing cryptographic hardware . 16
7.6.7 End of TSU key life cycle . 16
7.7 Time-stamping . 16
7.7.1 Time-stamp issuance. 16
7.7.2 Clock synchronization with UTC . 17
7.8 Physical and environmental security . 17
7.9 Operation security . 18
7.10 Network security . 18
7.11 Incident management . 18
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4 ETSI EN 319 421 V1.1.1 (2016-03)
7.12 Collection of evidence . 18
7.13 Business continuity management . 19
7.14 TSA termination and termination plans . 19
7.15 Compliance. 19
8 Additional requirements for qualified electronic time-stamps as per Regulation (EU) No 910/2014 . 19
8.1 TSU public key certificate . 19
8.2 TSA issuing non-qualified and qualified electronic time-stamps as per Regulation (EU) No 910/2014 . 20
Annex A (informative): Potential liability in the provision of time-stamping services . 21
Annex B (informative): Model TSA disclosure statement . 22
B.1 Introduction . 22
B.2 TSA disclosure statement structure . 22
Annex C (informative): Coordinated Universal Time (UTC). 24
Annex D (informative): Long term verification of time-stamps . 25
Annex E (informative): Regulation (EU) No 910/2014 and qualified electronic time-stamp
policy cross-reference . 26
Annex F (informative): Possible implementation architectures - time-stamping service . 27
F.1 Managed time-stamping service . 27
F.2 Selective alternative quality . 27
Annex G (informative): Major changes from ETSI TS 102 023 . 29
Annex H (informative): Conformity Assessment Check list . 30
History . 31
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5 ETSI EN 319 421 V1.1.1 (2016-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (EN) has been produced by ETSI Technical Committee Electronic Signatures and
Infrastructures (ESI).
The present document was previously published as ETSI TS 102 023 [i.8].
National transposition dates
Date of adoption of this EN: 22 February 2016
Date of latest announcement of this EN (doa): 31 May 2016
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 30 November 2016
Date of withdrawal of any conflicting National Standard (dow): 30 June 2017
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The present document is aiming to meet the general requirements of the international community to provide trust and
confidence in electronic transactions including, amongst others, applicable requirements from Regulation (EU)
No 910/2014 [i.4].
The Regulation includes requirements for Trust Service Providers (TSP) providing services to the public, including
TSPs issuing time-stamps. Additionally, more specific requirements are identified in the Regulation for a specific class
of TSP called a Qualified TSP, with further specific requirements for those Qualified TSPs which issue qualified
time-stamps. The present document is aimed to meet the requirements of the Regulation for both Qualified and
non-Qualified TSPs issuing Qualified and non-Qualified electronic time-stamps respectively.
In order to verify an electronic signature, it can be necessary to prove that the signature from the signer was applied
when the signer's certificate was valid. This is necessary in two circumstances:
1) during the validity period of the signer's certificate, should the signer's certificate be revoked before the end of
its validity, e.g. because the signer's private key has been compromised;
2) after the end of the validity period of the signer's certificate, since CAs are not mandated to process revocation
status information beyond the end of the validity period of the certificates they have issued.
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6 ETSI EN 319 421 V1.1.1 (2016-03)
One method consists to use a time-stamp which allows proving that a datum existed before a particular time. This
technique allows proving that the signature was generated before the date contained in the time-stamp. Policy
requirements to cover that case are the primary aim of the present document.
However, these policy requirements allow addressing other needs.
Time-stamping is gaining an increasing interest by the business sector and is becoming an important component of
digital signatures, this is commonly based upon the Time-Stamp protocol from the IETF RFC 3161 [i.2] which is
profiled in ETSI EN 319 422 [5]. Agreed minimum security and quality requirements are necessary in order to ensure
trustworthy validation of long-term digital signatures.
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7 ETSI EN 319 421 V1.1.1 (2016-03)
1 Scope
The present document specifies policy and security requirements relating to the operation and management practices of
TSPs issuing time-stamps.
These policy requirements are applicable to TSPs issuing time-stamps. Such time-stamps can be used in support of
digital signatures or for any application requiring to prove that a datum existed before a particular time.
The present document can be used by independent bodies as the basis for confirming that a TSP can be trusted for
issuing time-stamps.
The present document does not specify:
• protocols used to access the TSUs;
NOTE 1: A time-stamping protocol is defined in IETF RFC 3161 [i.2] including optional update in IETF
RFC 5816 [i.3] and profiled in ETSI EN 319 422 [5].
• how the requirements identified herein can be assessed by an independent body;
• requirements for information to be made available to such independent bodies;
• requirements on such independent bodies.
NOTE 2: See ETSI EN 319 403 [i.9].
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
[1] Recommendation ITU-R TF.460-6 (2002): "Standard-frequency and time-signal emissions".
[2] ISO/IEC 19790:2012: "Information technology -- Security techniques -- Security requirements for
cryptographic modules".
[3] ISO/IEC 15408 (parts 1 to 3): "Information technology -- Security techniques -- Evaluation criteria
for IT security".
[4] ETSI EN 319 401: "Electronic Signatures and Infrastructures (ESI); General Policy Requirements
for Trust Service Providers".
[5] ETSI EN 319 422: "Electronic Signatures and Infrastructures (ESI); Time-stamping protocol and
time-stamp token profiles".
[6] FIPS PUB 140-2 (2001): "Security Requirements for Cryptographic Modules".
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8 ETSI EN 319 421 V1.1.1 (2016-03)
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 319 122-1: "Electronic Signatures and Infrastructures (ESI); CAdES digital signatures;
Part 1: Building blocks and CAdES baseline signatures".
[i.2] IETF RFC 3161 (2001): "Internet X.509 Public Key Infrastructure: Time-Stamp Protocol (TSP)".
[i.3] IETF RFC 5816: "ESSCertIDV2 update to RFC 3161".
[i.4] Regulation (EU) No 910/2014 of the European Parliament and of the Council on electronic
identification and trust services for electronic transactions in the internal market and repealing
Directive 1999/93/EC.
[i.5] Council Directive 93/13/EEC of 5 April 1993 on unfair terms in consumer contracts.
[i.6] BIPM Circular T.
NOTE: Available from the BIPM website http://www.bipm.org/.
[i.7] ETSI TS 119 312: "Electronic Signatures and Infrastructures (ESI); Cryptographic Suites".
[i.8] ETSI TS 102 023: "Electronic Signatures and Infrastructures (ESI); Policy requirements for time-
stamping authorities".
[i.9] ETSI EN 319 403: "Electronic Signatures and Infrastructures (ESI); Trust Service Provider
Conformity Assessment - Requirements for conformity assessment bodies assessing Trust Service
Providers".
[i.10] ETSI EN 319 411-1: "Electronic Signatures and Infrastructures (ESI); Policy and security
requirements for Trust Service Providers issuing certificates; Part 1: General requirements".
[i.11] ETSI EN 319 411-2: "Electronic Signatures and Infrastructures (ESI); Policy and security
requirements for Trust Service Providers issuing certificates; Part 2: Requirements for trust service
providers issuing EU qualified certificates".
[i.12] CEN EN 419 231: "Protection profile for trustworthy systems supporting time stamping".
[i.13] CEN EN 419 221-2: "Protection profiles for TSP Cryptographic modules - Part 2: Cryptographic
module for CSP signing operations with backup".
[i.14] CEN EN 419 221-3: "Protection profiles for TSP Cryptographic modules - Part 3: Cryptographic
module for Cryptographic module for CSP key generation services".
[i.15] CEN EN 419 221-4: "Protection profiles for TSP Cryptographic modules - Part 4: Cryptographic
module for CSP signing operations without backup".
[i.16] CEN EN 419 221-5: "Protection profiles for TSP Cryptographic modules - Part 5: Cryptographic
module for trust services".
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9 ETSI EN 319 421 V1.1.1 (2016-03)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given ETSI EN 319 401 [4] and the following
apply:
NOTE: Where a definition is copied from a referenced document this is indicated by inclusion of the reference
identifier number at the end of the definition.
Coordinated Universal Time (UTC): time scale based on the second as defined in Recommendation ITU-R
TF.460-6 [1]
NOTE: For most practical purposes UTC is equivalent to mean solar time at the prime meridian (0°). More
specifically, UTC is a compromise between the highly stable atomic time (Temps Atomique International
- TAI) and solar time derived from the irregular Earth rotation (related to the Greenwich mean sidereal
time (GMST) by a conventional relationship) (see annex C for more details).
relying party: recipient of a time-stamp who relies on that time-stamp
subscriber: legal or natural person to whom a time-stamp is issued and who is bound to any subscriber obligations
time-stamp: data in electronic form which binds other electronic data to a particular time establishing evidence that
these data existed at that time
time-stamp policy: named set of rules that indicates the applicability of a time-stamp to a particular community and/or
class of application with common security requirements
NOTE: This is a specific type of trust service policy as defined in ETSI EN 319 401 [4].
Time-Stamping Authority (TSA): TSP providing time-stamping services using one or more time-stamping units
Time-stamping service: trust service for issuing time-stamps
Time-Stamping Unit (TSU): set of hardware and software which is managed as a unit and has a single time-stamp
signing key active at a time
trust service: electronic service that enhances trust and confidence in electronic transactions
Trust Service Provider (TSP): entity which provides one or more trust services
TSA Disclosure statement: set of statements about the policies and practices of a TSA that particularly require
emphasis or disclosure to subscribers and relying parties, for example to meet regulatory requirements
TSA practice statement: statement of the practices that a TSA employs in issuing time-stamp
NOTE: This is a specific type of trust service practice statement as defined in ETSI EN 319 401 [4].
TSA system: composition of IT products and components organized to support the provision of time-stamping services
UTC(k): time scale realized by the laboratory "k" and kept in close agreement with UTC, with the goal to reach
±100 ns.
NOTE: A list of UTC(k) laboratories is given in clause 1 of Circular T [i.6] disseminated by BIPM and available
from the BIPM website (http://www.bipm.org/).
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in ETSI EN 319 401 [4] and the following apply:
BIPM Bureau International des Poids et Mesures
BTSP Best practices Time-Stamp Policy
CA Certification Authority
GMT Greenwich Mean Time
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10 ETSI EN 319 421 V1.1.1 (2016-03)
IERS International Earth Rotation and Reference System Service
IT Information Technology
TAI International Atomic Time
TSA Time-Stamping Authority
TSP Trust Service Provider
TSU Time-Stamping Unit
UTC Coordinated Universal Time
4 General concepts
4.1 General policy requirements concepts
The present document references ETSI EN 319 401 [4] for generic policy requirements common to all classes of trust
service providers service.
These policy requirements are based upon the use of public key cryptography, public key certificates and reliable time
sources.
Subscriber and relying parties are expected to consult the TSA's practice statement to obtain further details of precisely
how this time-stamp policy is implemented by the particular TSA (e.g. protocols used in providing this service).
4.2 Time-stamping services
The provision of time-stamping services is broken down in the present document into the following component services
for the purposes of classifying requirements:
• Time-stamping provision: This service component generates time-stamps.
• Time-stamping management: This service component monitors and controls the operation of the
time-stamping services to ensure that the service provided is as specified by the TSA. This service component
has responsibility for the installation and de-installation of the time-stamping provision service.
EXAMPLE: Time-stamping management ensures that the clock used for time-stamping is correctly
synchronized with UTC.
This subdivision of services is only for the purposes of clarifying the requirements specified in the present document
and places no restrictions on any subdivision of an implementation of time-stamping services.
4.3 Time-Stamping Authority (TSA)
A Trust Service Provider (TSP) providing time-stamping services to the public, is called the Time-Stamping Authority
(TSA). The TSA has overall responsibility for the provision of the time-stamping services identified in clause 4.2. The
TSA has responsibility for the operation of one or more TSUs which creates and signs on behalf of the TSA. The TSA
responsible for issuing a time-stamp is identifiable (see clause 7.7.1, d).
The TSA may make use of other parties to provide parts of the time-stamping services. However, the TSA always
maintains overall responsibility (as per clause 6.5) and ensures that the policy requirements identified in the present
document are met.
EXAMPLE: A TSA sub-contracts all the component services, including the services which generate time-
stamps using the TSU's keys. However, the private key or keys used to generate the time-stamps
are identified as belonging to the TSA which maintains overall responsibility for meeting the
requirements defined in the present document.
A TSA may operate several identifiable time-stamping units.
A TSA is a trust service provider as described in ETSI EN 319 401 [4] which issues time-stamps.
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11 ETSI EN 319 421 V1.1.1 (2016-03)
4.4 Subscriber
When the subscriber is an organization, it comprises several end-users or an individual end-user and some of the
obligations that apply to that organization will have to apply as well to the end-users. In any case the organization will
be held responsible if the obligations from the end-users are not correctly fulfilled and therefore such an organization is
expected to suitably inform its end users.
When the subscriber is an end-user, the end-user will be held directly responsible if its obligations are not correctly
fulfilled.
4.5 Time-stamp policy and TSA practice statement
This clause explains the relative roles of time-stamp policy and TSA practice statement. It places no restriction on the
form of a time-stamp policy or practice statement specification.
A time-stamp policy is a form of Trust Service Policy as specified in ETSI EN 319 401 [4] applicable to trust service
providers issuing time-stamps.
TSA Practice Statement is a form of Trust Service Practice Statement as specified in ETSI EN 319 401 [4] applicable to
trust service providers issuing time-stamps.
The present document specifies a time-stamp policy to meet general requirements for trusted time-stamping services.
TSAs specify in TSA practice statements how these requirements are met.
5 Introduction to time-stamp policies and general
requirements
5.1 General
The policy requirements are defined in the present document in terms of a time-stamp policy. The present document
specifies one time-stamp policy: a best practices time-stamp policy (BTSP) for TSAs issuing time-stamps, supported by
public key certificates, with an accuracy of 1 second or better.
A TSA may define its own policy which enhances a policy defined in the present document. Such a policy shall
incorporate or further constrain the requirements identified in the present document.
If an accuracy of better than 1 second is provided by the TSA then the accuracy shall be indicated in the TSA's
disclosure statement (see clause 6.3) and in each time-stamp issued to an accuracy of better than 1 second.
5.2 Identification
The identifier of the time-stamp policy specified in the present document is:
a) BTSP : a best practices policy for time-stamp.
itu-t(0) identified-organization(4) etsi(0)
time-stamp-policy(2023)
policy-identifiers(1) best-practices-ts-policy (1)
By including this object identifier in a time-stamp, the TSA claims conformance to the identified time-stamp policy.
A TSA shall include the identifier for the time-stamp policy being supported in the TSA disclosure statement made
available to subscribers and relying parties to indicate its claim of conformance.
When the TSA uses its own identifier for the time-stamp policy, the TSA shall indicate in its policy document and in its
TSA disclosure statement, the ETSI time-stamping identifier (i.e. BSTP) being supported.
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12 ETSI EN 319 421 V1.1.1 (2016-03)
5.3 User community and applicability
5.3.1 Best practices time-stamp policy
This policy is aimed at meeting the requirements of time-stamp for long term validity (e.g. as defined in ETSI
EN 319 122 [i.1]) but is generally applicable to any use which has a requirement for equivalent quality.
This policy may be used for public time-stamping services or time-stamping services used within a closed community.
6 Policies and practices
6.1 Risk assessment
The requirements identified in ETSI EN 319 401 [4], clause 5 shall apply.
6.2 Trust Service Practice Statement
The requirements identified in ETSI EN 319 401 [4], clause 6.1 shall apply.
In addition, the statement shall at least specify for each time-stamp policy supported by the TSA:
a) at least one hashing algorithm used to represent the datum being time-stamped;
b) the accuracy of the time in the time-stamps with respect to UTC;
c) any limitations on the use of the time-stamping service;
d) the subscriber's obligations as defined in clause 6.5.2, if any;
e) the relying party's obligations as defined in clause 6.6;
f) information on how to verify the time-stamp such that the relying party is considered to "reasonably rely" on
the time-stamp (see clause 6.6) and any possible limitations on the validity period; and
g) any claim to meet the requirements on time-stamping services under national law.
The TSA should include in its time-stamping disclosure statement availability of its service.
EXAMPLE: Expected mean time between failure of the time-stamping service, expected mean time to recovery
following a failure and provisions made for disaster recovery including back-up services.
The model TSA disclosure statement given in annex B may be used. Alternatively this may be provided as part of a
subscriber/relying party agreement.
The TSA disclosure statement may be included in a TSA practice statement provided that it is conspicuous to the
reader.
6.3 Terms and conditions
The general obligations specified in ETSI EN 319 401 [4], clause 6.2 shall apply.
6.4 Information security policy
The requirements identified in ETSI EN 319 401 [4], clause 6.3 shall apply.
6.5 TSA obligations
6.5.1 General
The TSA shall adhere to any additional obligations indicated in the time-stamp either directly or incorporated by
reference.
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13 ETSI EN 319 421 V1.1.1 (2016-03)
6.5.2 TSA obligations towards subscribers
The present document places no specific obligations on the subscriber beyond any TSA specific requirements stated in
the TSA's terms and conditions.
6.6 Information for relying parties
The terms and conditions made available to relying parties (see clause 6.3) shall include an obligation on the relying
party, when relying on a time-stamp, to:
a) verify that the time-stamp has been correctly signed and that the private key used to sign the time-stamp has
not been compromised until the time of the verification;
NOTE: During the TSU's certificate validity period, the validity of the signing key can be checked using current
revocation status for the TSU's certificate. If the time of verification exceeds the end of the validity period
of the corresponding certificate, see annex D for guidance.
b) take into account any limitations on the usage of the time-stamp indicated by the time-stamp policy; and
c) take into account any other precautions prescribed in agreements or elsewhere.
7 TSA management and operation
7.1 Introduction
These policy requirements are not meant to imply any restrictions on charging for TSA services.
The requirements are indicated in terms of the security objectives followed by more specific requirements for controls
to meet those objectives where considered necessary to provide the necessary confidence that those objective will be
met.
NOTE: The details of controls required to meet an objective is a balance between achieving the necessary
confidence whilst minimizing the restrictions on the techniques that a TSA can employ in issuing
time-stamps. In ETSI EN 319 401 [4], reference is made to other more general standards which can be
used as a source of more detailed control requirements. Due to these factors the specificity of the
requirements given under a given topic can vary.
The provision of a time-stamp in response to a request is at the discretion of the TSA depending on any service level
agreements with the subscriber.
7.2 Internal organization
The requirements identified in ETSI EN 319 401 [4], clause 7.1 shall apply. In addition the following particular
requirements apply:
a) The TSA shall be a legal entity according to national law.
b) The TSA shall have a system or systems for quality and information security management appropriate for the
time-stamping services it is providing.
c) It shall employ a sufficient number of personnel having the necessary education, training, technical knowledge
and experience relating to the type, range and volume of work necessary to provide time-stamping services.
NOTE: Personnel employed by a TSA include individual personnel contractually engaged in performing
functions in support of the TSA's time-stamping services. Personnel who are involved only in monitoring
the TSA services need not be TSA personnel.
7.3 Personnel security
The requirements identified in ETSI EN 319 401 [4], clause 7.2 shall apply.
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14 ETSI EN 319 421 V1.1.1 (2016-03)
7.4 Asset management
The requirements identified in ETSI EN 319 401 [4], clause 7.3 shall apply.
7.5 Access control
The requirements identified in ETSI EN 319 401 [4], clause 7.4 shall apply.
7.6 Cryptographic controls
7.6.1 General
The requirements identified in ETSI EN 319 401 [4], clause 7.5 shall apply.
7.6.2 TSU key generation
The following particular requirements apply:
a) The generation of the TSU's signing key(s) shall be undertaken in a physically secured environment (as per
clause 7.8) by personnel in trusted roles (as per clause 7.3) under, at least, dual control. The personnel
authorized to carry out this function shall be limited to those required to do so under the TSA's practices.
b) The generation of the TSU's signing key(s) shall be carried out within a secure cryptographic device which:
i) is a trustworthy system which is assured to EAL 4 or higher in accordance with ISO/IEC 15408 [3], or
equivalent national or internationally recognized evaluation criteria for IT security. This shall be to a
security target or protection profile which meets the requirements of the present document, based on a
risk analysis and taking into account physical and other non-technical security measures; or
NOTE 1: Standards specifying common criteria protection profiles for TSP cryptographic modules, in accordance
with ISO/IEC 15408 [3], are currently under development within CEN as CEN TS 419 221-2 [i.13],
CEN TS 419 221-3 [i.14], CEN TS 419 221-4 [i.15], or CEN EN 419 221-5 [i.16].
ii) meets the requirements identified in ISO/IEC 19790 [2] or FIPS PUB 140-2 [6], level 3.
The secure cryptographic device should be as per i).
NOTE 2: With the general availability of devices which meet ISO/IEC 15408 [3], it is expected that
ISO/IEC 19790 [2] or FIPS 140-2 [6] level 3 will no longer be acceptable.
c) The TSU key generation algorithm, the resulting signing key length and signature algorithm used for signing
time-stamps key should be as specified in ETSI TS 119 312 [i.7].
NOTE 3: Cryptographic suites recommendations defined in ETSI TS 119 312 [i.7] can be superseded by national
recommendations.
d) A TSU's signing key should not be imported into different cryptographic modules.
e) If there are same keys in different cryptographic modules, they shall be associated with the same public key
certificate into all the different cryptographic modules.
f) A TSU shall have a single time-stamp signing key active at a time.
NOTE 4: A set of hardware and software can manage different TSUs.
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15 ETSI EN 319 421 V1.1.1 (2016-03)
7.6.3 TSU private key protection
The TSU private keys shall remain confidential and their integrity shall be maintained with at least the following
particular requirements:
a) The TSU private signing key shall be held and used within a cryptographic module which:
i) is a trustworthy system which is assured to EAL 4 or higher in accordance with ISO/IEC 15408 [3], or
equivalent national or internationally recognized evaluation criteria for IT security. This shall be to a
security target or protection profile which meets the requirements of the present document, based on a
risk analysis and taking into account physical and other non-technical security measures; or
NOTE 1: Standards specifying common criteria protection profiles for TSP cryptographic modules, in accordance
with ISO/IEC 15408 [3], are currently under development within CEN as CEN TS 419 221-2 [i.13],
CEN TS 419 221-3 [i.14], CEN TS 419 221-4 [i.15], or CEN EN 419 221-5 [i.16].
ii) meets the requirements identified in ISO/IEC 19790 [2] or FIPS PUB 140-2 [6], level 3.
The secure cryptographic device should be as per i).
NOTE 2: With the general availability of devices which meet ISO/IEC 15408 [3], it is expected that
ISO/IEC 19790 [2] or FIPS 140-2 [6] level 3 will no longer be acceptable.
b) If TSU private keys are backed up, they shall be copied, stored and recovered only by personnel in trusted
roles using, at least, dual control in a physically secured environment (see clause 7.8). The personnel
authorized to carry out this function shall be limited to those required to do so under the TSA's practices.
c) Any backup copies of the TSU private signing keys shall be protected to ensure its integrity and confidentiality
by the cryptographic module before being stored outside that device.
NOTE 3: Additional requirement for private key protection may be defined in the future following on the
agreement of a time-stamping protection profile to be CEN EN 419 231 [i.12].
7.6.4 TSU public key certificate
The TSA shall guarantee the integrity and authenticity of the TSU signature verification (public) keys with at least the
following particular requirements:
a) TSU signature verification (public) keys shall be made available to relying parties in a public key certificate.
b) The TSU signature verification (public) key certificate should be issued by a certification authority operating
under ETSI EN 319 411-1 [i.10].
c) The TSU shall not issue time-stamp before its signature verification (public key) certificate is loaded into the
TSU or its cryptographic device.
When obtaining a signature verification (public key) certificate, the TSA should verify that this certificate has been
correctly signed (including verification of the certificate chain to a trusted certification authority).
7.6.5 Rekeying TSU's key
The validity period of TSU's certificate shall not be longer than the period of time that the chosen algorithm and key
length is recognized as being fit for purpose (see clause 7.6.2c).
NOTE 1: Concerns and considerations when limiting that lifetime; the longer the validity period of the TSU
certificates will be, the longer the size of the records to be kept will be. Should a TSU private key or
certificate be compromised, the older the TSU certificate the more time-stamps will be affected.
NOTE 2: TSU key compromise does not only depend on the characteristics of the cryptographic module being used
but also on the procedures being used at system initialization and key export (when that function is
supported).
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16 ETSI EN 319 421 V1.1.1 (2016-03)
7.6.6 Life cycle management of signing cryptographic hardware
The following particular requirements apply:
a) Time-stamp signing cryptographic hardware shall not be tampered with during shipment.
b) Time-stamp signing cryptographic hardware shall not be tampered with when and while stored.
c) Instal
...
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Electronic Signatures and Infrastructures (ESI) - Policy and Security Requirements for Trust Service Providers issuing Time-Stamps35.040.01Kodiranje informacij na splošnoInformation coding in general35.030Informacijska varnostIT SecurityICS:Ta slovenski standard je istoveten z:ETSI EN 319 421 V1.1.1 (2016-03)SIST EN 319 421 V1.1.1:2016en01-junij-2016SIST EN 319 421 V1.1.1:2016SLOVENSKI
STANDARD
EUROPEAN STANDARD SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 2
Reference DEN/ESI-0019421 Keywords e-commerce, electronic signature, security, time-stamping, trust services ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE
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© European Telecommunications Standards Institute 2016. All rights reserved.
DECTTM, PLUGTESTSTM, UMTSTM and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 3 Contents Intellectual Property Rights . 5 Foreword . 5 Modal verbs terminology . 5 Introduction . 5 1 Scope . 7 2 References . 7 2.1 Normative references . 7 2.2 Informative references . 8 3 Definitions and abbreviations . 9 3.1 Definitions . 9 3.2 Abbreviations . 9 4 General concepts . 10 4.1 General policy requirements concepts . 10 4.2 Time-stamping services . 10 4.3 Time-Stamping Authority (TSA) . 10 4.4 Subscriber . 11 4.5 Time-stamp policy and TSA practice statement . 11 5 Introduction to time-stamp policies and general requirements . 11 5.1 General . 11 5.2 Identification . 11 5.3 User community and applicability . 12 5.3.1 Best practices time-stamp policy . 12 6 Policies and practices . 12 6.1 Risk assessment . 12 6.2 Trust Service Practice Statement . 12 6.3 Terms and conditions . 12 6.4 Information security policy . 12 6.5 TSA obligations . 12 6.5.1 General . 12 6.5.2 TSA obligations towards subscribers . 13 6.6 Information for relying parties . 13 7 TSA management and operation . 13 7.1 Introduction . 13 7.2 Internal organization. 13 7.3 Personnel security. 13 7.4 Asset management . 14 7.5 Access control . 14 7.6 Cryptographic controls . 14 7.6.1 General . 14 7.6.2 TSU key generation . 14 7.6.3 TSU private key protection . 15 7.6.4 TSU public key certificate . 15 7.6.5 Rekeying TSU's key . 15 7.6.6 Life cycle management of signing cryptographic hardware . 16 7.6.7 End of TSU key life cycle . 16 7.7 Time-stamping . 16 7.7.1 Time-stamp issuance. 16 7.7.2 Clock synchronization with UTC . 17 7.8 Physical and environmental security . 17 7.9 Operation security . 18 7.10 Network security . 18 7.11 Incident management . 18 SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 4 7.12 Collection of evidence . 18 7.13 Business continuity management . 19 7.14 TSA termination and termination plans . 19 7.15 Compliance. 19 8 Additional requirements for qualified electronic time-stamps as per Regulation (EU) No 910/2014 . 19 8.1 TSU public key certificate . 19 8.2 TSA issuing non-qualified and qualified electronic time-stamps as per Regulation (EU) No 910/2014 . 20 Annex A (informative): Potential liability in the provision of time-stamping services . 21 Annex B (informative): Model TSA disclosure statement . 22 B.1 Introduction . 22 B.2 TSA disclosure statement structure . 22 Annex C (informative): Coordinated Universal Time (UTC). 24 Annex D (informative): Long term verification of time-stamps . 25 Annex E (informative): Regulation (EU) No 910/2014 and qualified electronic time-stamp policy cross-reference . 26 Annex F (informative): Possible implementation architectures - time-stamping service . 27 F.1 Managed time-stamping service . 27 F.2 Selective alternative quality . 27 Annex G (informative): Major changes from ETSI TS 102 023 . 29 Annex H (informative): Conformity Assessment Check list . 30 History . 31
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 5 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (https://ipr.etsi.org/). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This European Standard (EN) has been produced by ETSI Technical Committee Electronic Signatures and Infrastructures (ESI). The present document was previously published as ETSI TS 102 023 [i.8].
National transposition dates Date of adoption of this EN: 22 February 2016 Date of latest announcement of this EN (doa): 31 May 2016 Date of latest publication of new National Standard or endorsement of this EN (dop/e):
30 November 2016 Date of withdrawal of any conflicting National Standard (dow): 30 June 2017
Modal verbs terminology In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). "must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation. Introduction The present document is aiming to meet the general requirements of the international community to provide trust and confidence in electronic transactions including, amongst others, applicable requirements from Regulation (EU) No 910/2014 [i.4]. The Regulation includes requirements for Trust Service Providers (TSP) providing services to the public, including TSPs issuing time-stamps. Additionally, more specific requirements are identified in the Regulation for a specific class of TSP called a Qualified TSP, with further specific requirements for those Qualified TSPs which issue qualified time-stamps. The present document is aimed to meet the requirements of the Regulation for both Qualified and non-Qualified TSPs issuing Qualified and non-Qualified electronic time-stamps respectively. In order to verify an electronic signature, it can be necessary to prove that the signature from the signer was applied when the signer's certificate was valid. This is necessary in two circumstances: 1) during the validity period of the signer's certificate, should the signer's certificate be revoked before the end of its validity, e.g. because the signer's private key has been compromised; 2) after the end of the validity period of the signer's certificate, since CAs are not mandated to process revocation status information beyond the end of the validity period of the certificates they have issued. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 6 One method consists to use a time-stamp which allows proving that a datum existed before a particular time. This technique allows proving that the signature was generated before the date contained in the time-stamp. Policy requirements to cover that case are the primary aim of the present document. However, these policy requirements allow addressing other needs. Time-stamping is gaining an increasing interest by the business sector and is becoming an important component of digital signatures, this is commonly based upon the Time-Stamp protocol from the IETF RFC 3161 [i.2] which is profiled in ETSI EN 319 422 [5]. Agreed minimum security and quality requirements are necessary in order to ensure trustworthy validation of long-term digital signatures. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 7 1 Scope The present document specifies policy and security requirements relating to the operation and management practices of TSPs issuing time-stamps. These policy requirements are applicable to TSPs issuing time-stamps. Such time-stamps can be used in support of digital signatures or for any application requiring to prove that a datum existed before a particular time. The present document can be used by independent bodies as the basis for confirming that a TSP can be trusted for issuing time-stamps. The present document does not specify: • protocols used to access the TSUs; NOTE 1: A time-stamping protocol is defined in IETF RFC 3161 [i.2] including optional update in IETF RFC 5816 [i.3] and profiled in ETSI EN 319 422 [5]. • how the requirements identified herein can be assessed by an independent body; • requirements for information to be made available to such independent bodies; • requirements on such independent bodies. NOTE 2: See ETSI EN 319 403 [i.9]. 2 References 2.1 Normative references References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long term validity. The following referenced documents are necessary for the application of the present document. [1] Recommendation ITU-R TF.460-6 (2002): "Standard-frequency and time-signal emissions". [2] ISO/IEC 19790:2012: "Information technology -- Security techniques -- Security requirements for cryptographic modules". [3] ISO/IEC 15408 (parts 1 to 3): "Information technology -- Security techniques -- Evaluation criteria for IT security". [4] ETSI EN 319 401: "Electronic Signatures and Infrastructures (ESI); General Policy Requirements for Trust Service Providers". [5] ETSI EN 319 422: "Electronic Signatures and Infrastructures (ESI); Time-stamping protocol and time-stamp token profiles". [6] FIPS PUB 140-2 (2001): "Security Requirements for Cryptographic Modules". SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 8 2.2 Informative references References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long term validity. The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] ETSI EN 319 122-1: "Electronic Signatures and Infrastructures (ESI); CAdES digital signatures; Part 1: Building blocks and CAdES baseline signatures". [i.2] IETF RFC 3161 (2001): "Internet X.509 Public Key Infrastructure: Time-Stamp Protocol (TSP)". [i.3] IETF RFC 5816: "ESSCertIDV2 update to RFC 3161". [i.4] Regulation (EU) No 910/2014 of the European Parliament and of the Council on electronic identification and trust services for electronic transactions in the internal market and repealing Directive 1999/93/EC. [i.5] Council Directive 93/13/EEC of 5 April 1993 on unfair terms in consumer contracts. [i.6] BIPM Circular T. NOTE: Available from the BIPM website http://www.bipm.org/. [i.7] ETSI TS 119 312: "Electronic Signatures and Infrastructures (ESI); Cryptographic Suites". [i.8] ETSI TS 102 023: "Electronic Signatures and Infrastructures (ESI); Policy requirements for time-stamping authorities". [i.9] ETSI EN 319 403: "Electronic Signatures and Infrastructures (ESI); Trust Service Provider Conformity Assessment - Requirements for conformity assessment bodies assessing Trust Service Providers". [i.10] ETSI EN 319 411-1: "Electronic Signatures and Infrastructures (ESI); Policy and security requirements for Trust Service Providers issuing certificates; Part 1: General requirements". [i.11] ETSI EN 319 411-2: "Electronic Signatures and Infrastructures (ESI); Policy and security requirements for Trust Service Providers issuing certificates; Part 2: Requirements for trust service providers issuing EU qualified certificates". [i.12] CEN EN 419 231: "Protection profile for trustworthy systems supporting time stamping". [i.13] CEN EN 419 221-2: "Protection profiles for TSP Cryptographic modules - Part 2: Cryptographic module for CSP signing operations with backup". [i.14] CEN EN 419 221-3: "Protection profiles for TSP Cryptographic modules - Part 3: Cryptographic module for Cryptographic module for CSP key generation services". [i.15] CEN EN 419 221-4: "Protection profiles for TSP Cryptographic modules - Part 4: Cryptographic module for CSP signing operations without backup". [i.16] CEN EN 419 221-5: "Protection profiles for TSP Cryptographic modules - Part 5: Cryptographic module for trust services". SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 9 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given ETSI EN 319 401 [4] and the following apply: NOTE: Where a definition is copied from a referenced document this is indicated by inclusion of the reference identifier number at the end of the definition. Coordinated Universal Time (UTC): time scale based on the second as defined in Recommendation ITU-R TF.460-6 [1] NOTE: For most practical purposes UTC is equivalent to mean solar time at the prime meridian (0°). More specifically, UTC is a compromise between the highly stable atomic time (Temps Atomique International - TAI) and solar time derived from the irregular Earth rotation (related to the Greenwich mean sidereal time (GMST) by a conventional relationship) (see annex C for more details). relying party: recipient of a time-stamp who relies on that time-stamp subscriber: legal or natural person to whom a time-stamp is issued and who is bound to any subscriber obligations time-stamp: data in electronic form which binds other electronic data to a particular time establishing evidence that these data existed at that time time-stamp policy: named set of rules that indicates the applicability of a time-stamp to a particular community and/or class of application with common security requirements NOTE: This is a specific type of trust service policy as defined in ETSI EN 319 401 [4]. Time-Stamping Authority (TSA): TSP providing time-stamping services using one or more time-stamping units Time-stamping service: trust service for issuing time-stamps Time-Stamping Unit (TSU): set of hardware and software which is managed as a unit and has a single time-stamp signing key active at a time trust service: electronic service that enhances trust and confidence in electronic transactions Trust Service Provider (TSP): entity which provides one or more trust services TSA Disclosure statement: set of statements about the policies and practices of a TSA that particularly require emphasis or disclosure to subscribers and relying parties, for example to meet regulatory requirements TSA practice statement: statement of the practices that a TSA employs in issuing time-stamp NOTE: This is a specific type of trust service practice statement as defined in ETSI EN 319 401 [4]. TSA system: composition of IT products and components organized to support the provision of time-stamping services UTC(k): time scale realized by the laboratory "k" and kept in close agreement with UTC, with the goal to reach ±100 ns. NOTE: A list of UTC(k) laboratories is given in clause 1 of Circular T [i.6] disseminated by BIPM and available from the BIPM website (http://www.bipm.org/). 3.2 Abbreviations For the purposes of the present document, the abbreviations given in ETSI EN 319 401 [4] and the following apply: BIPM Bureau International des Poids et Mesures BTSP Best practices Time-Stamp Policy CA Certification Authority GMT Greenwich Mean Time SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 10 IERS International Earth Rotation and Reference System Service IT Information Technology TAI International Atomic Time TSA Time-Stamping Authority TSP Trust Service Provider TSU Time-Stamping Unit UTC Coordinated Universal Time 4 General concepts 4.1 General policy requirements concepts The present document references ETSI EN 319 401 [4] for generic policy requirements common to all classes of trust service providers service. These policy requirements are based upon the use of public key cryptography, public key certificates and reliable time sources. Subscriber and relying parties are expected to consult the TSA's practice statement to obtain further details of precisely how this time-stamp policy is implemented by the particular TSA (e.g. protocols used in providing this service). 4.2 Time-stamping services The provision of time-stamping services is broken down in the present document into the following component services for the purposes of classifying requirements: • Time-stamping provision: This service component generates time-stamps. • Time-stamping management: This service component monitors and controls the operation of the time-stamping services to ensure that the service provided is as specified by the TSA. This service component has responsibility for the installation and de-installation of the time-stamping provision service. EXAMPLE: Time-stamping management ensures that the clock used for time-stamping is correctly synchronized with UTC. This subdivision of services is only for the purposes of clarifying the requirements specified in the present document and places no restrictions on any subdivision of an implementation of time-stamping services. 4.3 Time-Stamping Authority (TSA) A Trust Service Provider (TSP) providing time-stamping services to the public, is called the Time-Stamping Authority (TSA). The TSA has overall responsibility for the provision of the time-stamping services identified in clause 4.2. The TSA has responsibility for the operation of one or more TSUs which creates and signs on behalf of the TSA. The TSA responsible for issuing a time-stamp is identifiable (see clause 7.7.1, d). The TSA may make use of other parties to provide parts of the time-stamping services. However, the TSA always maintains overall responsibility (as per clause 6.5) and ensures that the policy requirements identified in the present document are met. EXAMPLE: A TSA sub-contracts all the component services, including the services which generate time-stamps using the TSU's keys. However, the private key or keys used to generate the time-stamps are identified as belonging to the TSA which maintains overall responsibility for meeting the requirements defined in the present document. A TSA may operate several identifiable time-stamping units. A TSA is a trust service provider as described in ETSI EN 319 401 [4] which issues time-stamps. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 11 4.4 Subscriber When the subscriber is an organization, it comprises several end-users or an individual end-user and some of the obligations that apply to that organization will have to apply as well to the end-users. In any case the organization will be held responsible if the obligations from the end-users are not correctly fulfilled and therefore such an organization is expected to suitably inform its end users. When the subscriber is an end-user, the end-user will be held directly responsible if its obligations are not correctly fulfilled. 4.5 Time-stamp policy and TSA practice statement This clause explains the relative roles of time-stamp policy and TSA practice statement. It places no restriction on the form of a time-stamp policy or practice statement specification. A time-stamp policy is a form of Trust Service Policy as specified in ETSI EN 319 401 [4] applicable to trust service providers issuing time-stamps. TSA Practice Statement is a form of Trust Service Practice Statement as specified in ETSI EN 319 401 [4] applicable to trust service providers issuing time-stamps. The present document specifies a time-stamp policy to meet general requirements for trusted time-stamping services. TSAs specify in TSA practice statements how these requirements are met. 5 Introduction to time-stamp policies and general requirements 5.1 General The policy requirements are defined in the present document in terms of a time-stamp policy. The present document specifies one time-stamp policy: a best practices time-stamp policy (BTSP) for TSAs issuing time-stamps, supported by public key certificates, with an accuracy of 1 second or better. A TSA may define its own policy which enhances a policy defined in the present document. Such a policy shall incorporate or further constrain the requirements identified in the present document. If an accuracy of better than 1 second is provided by the TSA then the accuracy shall be indicated in the TSA's disclosure statement (see clause 6.3) and in each time-stamp issued to an accuracy of better than 1 second. 5.2 Identification The identifier of the time-stamp policy specified in the present document is: a) BTSP : a best practices policy for time-stamp. itu-t(0) identified-organization(4) etsi(0)
time-stamp-policy(2023)
policy-identifiers(1) best-practices-ts-policy (1)
By including this object identifier in a time-stamp, the TSA claims conformance to the identified time-stamp policy. A TSA shall include the identifier for the time-stamp policy being supported in the TSA disclosure statement made available to subscribers and relying parties to indicate its claim of conformance. When the TSA uses its own identifier for the time-stamp policy, the TSA shall indicate in its policy document and in its TSA disclosure statement, the ETSI time-stamping identifier (i.e. BSTP) being supported. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 12 5.3 User community and applicability 5.3.1 Best practices time-stamp policy This policy is aimed at meeting the requirements of time-stamp for long term validity (e.g. as defined in ETSI EN 319 122 [i.1]) but is generally applicable to any use which has a requirement for equivalent quality. This policy may be used for public time-stamping services or time-stamping services used within a closed community. 6 Policies and practices 6.1 Risk assessment The requirements identified in ETSI EN 319 401 [4], clause 5 shall apply. 6.2 Trust Service Practice Statement The requirements identified in ETSI EN 319 401 [4], clause 6.1 shall apply. In addition, the statement shall at least specify for each time-stamp policy supported by the TSA: a) at least one hashing algorithm used to represent the datum being time-stamped; b) the accuracy of the time in the time-stamps with respect to UTC; c) any limitations on the use of the time-stamping service; d) the subscriber's obligations as defined in clause 6.5.2, if any; e) the relying party's obligations as defined in clause 6.6; f) information on how to verify the time-stamp such that the relying party is considered to "reasonably rely" on the time-stamp (see clause 6.6) and any possible limitations on the validity period; and g) any claim to meet the requirements on time-stamping services under national law. The TSA should include in its time-stamping disclosure statement availability of its service. EXAMPLE: Expected mean time between failure of the time-stamping service, expected mean time to recovery following a failure and provisions made for disaster recovery including back-up services. The model TSA disclosure statement given in annex B may be used. Alternatively this may be provided as part of a subscriber/relying party agreement. The TSA disclosure statement may be included in a TSA practice statement provided that it is conspicuous to the reader. 6.3 Terms and conditions The general obligations specified in ETSI EN 319 401 [4], clause 6.2 shall apply. 6.4 Information security policy The requirements identified in ETSI EN 319 401 [4], clause 6.3 shall apply. 6.5 TSA obligations 6.5.1 General The TSA shall adhere to any additional obligations indicated in the time-stamp either directly or incorporated by reference. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 13 6.5.2 TSA obligations towards subscribers The present document places no specific obligations on the subscriber beyond any TSA specific requirements stated in the TSA's terms and conditions. 6.6 Information for relying parties The terms and conditions made available to relying parties (see clause 6.3) shall include an obligation on the relying party, when relying on a time-stamp, to: a) verify that the time-stamp has been correctly signed and that the private key used to sign the time-stamp has not been compromised until the time of the verification; NOTE: During the TSU's certificate validity period, the validity of the signing key can be checked using current revocation status for the TSU's certificate. If the time of verification exceeds the end of the validity period of the corresponding certificate, see annex D for guidance. b) take into account any limitations on the usage of the time-stamp indicated by the time-stamp policy; and c) take into account any other precautions prescribed in agreements or elsewhere. 7 TSA management and operation 7.1 Introduction These policy requirements are not meant to imply any restrictions on charging for TSA services. The requirements are indicated in terms of the security objectives followed by more specific requirements for controls to meet those objectives where considered necessary to provide the necessary confidence that those objective will be met. NOTE: The details of controls required to meet an objective is a balance between achieving the necessary confidence whilst minimizing the restrictions on the techniques that a TSA can employ in issuing time-stamps. In ETSI EN 319 401 [4], reference is made to other more general standards which can be used as a source of more detailed control requirements. Due to these factors the specificity of the requirements given under a given topic can vary. The provision of a time-stamp in response to a request is at the discretion of the TSA depending on any service level agreements with the subscriber. 7.2 Internal organization The requirements identified in ETSI EN 319 401 [4], clause 7.1 shall apply. In addition the following particular requirements apply: a) The TSA shall be a legal entity according to national law. b) The TSA shall have a system or systems for quality and information security management appropriate for the time-stamping services it is providing. c) It shall employ a sufficient number of personnel having the necessary education, training, technical knowledge and experience relating to the type, range and volume of work necessary to provide time-stamping services. NOTE: Personnel employed by a TSA include individual personnel contractually engaged in performing functions in support of the TSA's time-stamping services. Personnel who are involved only in monitoring the TSA services need not be TSA personnel. 7.3 Personnel security The requirements identified in ETSI EN 319 401 [4], clause 7.2 shall apply. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 14 7.4 Asset management The requirements identified in ETSI EN 319 401 [4], clause 7.3 shall apply. 7.5 Access control The requirements identified in ETSI EN 319 401 [4], clause 7.4 shall apply.
7.6 Cryptographic controls 7.6.1 General The requirements identified in ETSI EN 319 401 [4], clause 7.5 shall apply. 7.6.2 TSU key generation The following particular requirements apply: a) The generation of the TSU's signing key(s) shall be undertaken in a physically secured environment (as per clause 7.8) by personnel in trusted roles (as per clause 7.3) under, at least, dual control. The personnel authorized to carry out this function shall be limited to those required to do so under the TSA's practices. b) The generation of the TSU's signing key(s) shall be carried out within a secure cryptographic device which: i) is a trustworthy system which is assured to EAL 4 or higher in accordance with ISO/IEC 15408 [3], or equivalent national or internationally recognized evaluation criteria for IT security. This shall be to a security target or protection profile which meets the requirements of the present document, based on a risk analysis and taking into account physical and other non-technical security measures; or NOTE 1: Standards specifying common criteria protection profiles for TSP cryptographic modules, in accordance with ISO/IEC 15408 [3], are currently under development within CEN as CEN TS 419 221-2 [i.13], CEN TS 419 221-3 [i.14], CEN TS 419 221-4 [i.15], or CEN EN 419 221-5 [i.16]. ii) meets the requirements identified in ISO/IEC 19790 [2] or FIPS PUB 140-2 [6], level 3.
The secure cryptographic device should be as per i). NOTE 2: With the general availability of devices which meet ISO/IEC 15408 [3], it is expected that ISO/IEC 19790 [2] or FIPS 140-2 [6] level 3 will no longer be acceptable. c) The TSU key generation algorithm, the resulting signing key length and signature algorithm used for signing time-stamps key should be as specified in ETSI TS 119 312 [i.7]. NOTE 3: Cryptographic suites recommendations defined in ETSI TS 119 312 [i.7] can be superseded by national recommendations. d) A TSU's signing key should not be imported into different cryptographic modules.
e) If there are same keys in different cryptographic modules, they shall be associated with the same public key certificate into all the different cryptographic modules. f) A TSU shall have a single time-stamp signing key active at a time. NOTE 4: A set of hardware and software can manage different TSUs. SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 15 7.6.3 TSU private key protection The TSU private keys shall remain confidential and their integrity shall be maintained with at least the following particular requirements: a) The TSU private signing key shall be held and used within a cryptographic module which: i) is a trustworthy system which is assured to EAL 4 or higher in accordance with ISO/IEC 15408 [3], or equivalent national or internationally recognized evaluation criteria for IT security. This shall be to a security target or protection profile which meets the requirements of the present document, based on a risk analysis and taking into account physical and other non-technical security measures; or NOTE 1: Standards specifying common criteria protection profiles for TSP cryptographic modules, in accordance with ISO/IEC 15408 [3], are currently under development within CEN as CEN TS 419 221-2 [i.13], CEN TS 419 221-3 [i.14], CEN TS 419 221-4 [i.15], or CEN EN 419 221-5 [i.16]. ii) meets the requirements identified in ISO/IEC 19790 [2] or FIPS PUB 140-2 [6], level 3.
The secure cryptographic device should be as per i). NOTE 2: With the general availability of devices which meet ISO/IEC 15408 [3], it is expected that ISO/IEC 19790 [2] or FIPS 140-2 [6] level 3 will no longer be acceptable. b) If TSU private keys are backed up, they shall be copied, stored and recovered only by personnel in trusted roles using, at least, dual control in a physically secured environment (see clause 7.8). The personnel authorized to carry out this function shall be limited to those required to do so under the TSA's practices. c) Any backup copies of the TSU private signing keys shall be protected to ensure its integrity and confidentiality by the cryptographic module before being stored outside that device. NOTE 3: Additional requirement for private key protection may be defined in the future following on the agreement of a time-stamping protection profile to be CEN EN 419 231 [i.12]. 7.6.4 TSU public key certificate The TSA shall guarantee the integrity and authenticity of the TSU signature verification (public) keys with at least the following particular requirements: a) TSU signature verification (public) keys shall be made available to relying parties in a public key certificate. b) The TSU signature verification (public) key certificate should be issued by a certification authority operating under ETSI EN 319 411-1 [i.10]. c) The TSU shall not issue time-stamp before its signature verification (public key) certificate is loaded into the TSU or its cryptographic device. When obtaining a signature verification (public key) certificate, the TSA should verify that this certificate has been correctly signed (including verification of the certificate chain to a trusted certification authority). 7.6.5 Rekeying TSU's key The validity period of TSU's certificate shall not be longer than the period of time that the chosen algorithm and key length is recognized as being fit for purpose (see clause 7.6.2c). NOTE 1: Concerns and considerations when limiting that lifetime; the longer the validity period of the TSU certificates will be, the longer the size of the records to be kept will be. Should a TSU private key or certificate be compromised, the older the TSU certificate the more time-stamps will be affected.
NOTE 2: TSU key compromise does not only depend on the characteristics of the cryptographic module being used but also on the procedures being used at system initialization and key export (when that function is supported). SIST EN 319 421 V1.1.1:2016
ETSI ETSI EN 319 421 V1.1.1 (2016-03) 16 7.6.6 Life cycle management of signing cryptographic hardware The following particular requirements apply: a) Time-stamp signing cryptographic hardware shall not be tampered with during shipment. b) Time-stamp signing cryptographic hardware shall not be tampered with when and while stored. c) Installation, activation and duplication of TSU's signing keys in cryptographic hardware shall be done only by personnel in trusted roles using, at least, dual control in a physically secured environment (see clause 7.8). d) TSU private signing keys stored on TSU cryptographic module shall be erased upon device retirement in a way that it is practically impossible to recover them. 7.6.7 End of TSU key life cycle The TSA shall define an expiratio
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