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TECHNICAL SPECIFICATION
Electronic Signatures and Infrastructures (ESI);
Policy and Security Requirements for
Trust Service Providers issuing Time-Stamps
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2 ETSI TS 119 421 V1.0.1 (2015-07)
Reference
RTS/ESI-0019421-TS
Keywords
e-commerce, electronic signature, security,
time-stamping, trust services
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3 ETSI TS 119 421 V1.0.1 (2015-07)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 General concepts . 9
4.1 General policy requirements concepts . 9
4.2 Time-stamping services . 9
4.3 Time-Stamping Authority (TSA) . 9
4.4 Subscriber . 9
4.5 Time-stamp policy and TSA practice statement . 10
5 Introduction to time-stamp policies and general requirements . 10
5.1 General . 10
5.2 Identification . 10
5.3 User community and applicability . 10
5.3.1 Best practices time-stamp policy . 10
6 Policies and practices . 11
6.1 Risk assessment . 11
6.2 Trust Service Practice Statement . 11
6.3 Terms and conditions . 11
6.4 Information security policy . 11
6.5 TSA obligations . 11
6.5.1 General . 11
6.5.2 TSA obligations towards subscribers . 11
6.6 Information for relying parties . 12
7 TSA management and operation . 12
7.1 Introduction . 12
7.2 Internal organization. 12
7.3 Personnel security. 12
7.4 Asset management . 12
7.5 Access control . 13
7.6 Cryptographic controls . 13
7.6.1 General . 13
7.6.2 TSU key generation . 13
7.6.3 TSU private key protection . 13
7.6.4 TSU public key certificate . 14
7.6.5 Rekeying TSU's key . 14
7.6.6 Life cycle management of signing cryptographic hardware . 14
7.6.7 End of TSU key life cycle . 14
7.7 Time-stamping . 15
7.7.1 Time-stamp issuance. 15
7.7.2 Clock synchronization with UTC . 15
7.8 Physical and environmental security . 16
7.9 Operation security . 16
7.10 Network security . 17
7.11 Incident management . 17
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4 ETSI TS 119 421 V1.0.1 (2015-07)
7.12 Collection of evidence . 17
7.13 Business continuity management . 17
7.14 TSA termination and termination plans . 17
7.15 Compliance. 18
8 Additional requirements for Regulation (EU) No 910/2014 . 18
8.1 TSU public key certificate . 18
Annex A (informative): Potential liability in the provision of time-stamping services . 19
Annex B (informative): Model TSA disclosure statement . 20
B.1 Introduction . 20
B.2 TSA disclosure statement structure . 20
Annex C (informative): Coordinated Universal Time (UTC). 22
Annex D (informative): Long term verification of time-stamps . 23
Annex E (informative): Regulation (EU) No 910/2014 and qualified electronic time-stamp
policy cross-reference . 24
Annex F (informative): Possible implementation architectures - time-stamping service . 25
F.1 Managed time-stamping service . 25
F.2 Selective alternative quality . 25
Annex G (informative): Major changes from ETSI TS 102 023 . 27
Annex H (informative): Conformity Assessment Check list . 28
History . 29
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5 ETSI TS 119 421 V1.0.1 (2015-07)
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 Technical Specification (TS) 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].
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.
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 TS 119 422 [5]. Agreed minimum security and quality requirements are necessary in order to ensure
trustworthy validation of long-term digital signatures.
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6 ETSI TS 119 421 V1.0.1 (2015-07)
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 TS 119 422 [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 TS 119 403 [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.
[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 TS 119 401: "Electronic Signatures and Infrastructures (ESI); General Policy Requirements
for Trust Service Providers".
[5] ETSI TS 119 422: "Electronic Signatures and Infrastructures (ESI); Time-stamping protocol and
time-stamp profiles".
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7 ETSI TS 119 421 V1.0.1 (2015-07)
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 TS 119 122: "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 TS 119 403: "Electronic Signatures and Infrastructures (ESI); Trust Service Provider
Conformity Assessment - Requirements for conformity assessment bodies assessing Trust Service
Providers".
[i.11] ETSI TS 119 411-1: "Electronic Signatures and Infrastructures (ESI); Policy and security
requirements for Trust Service Providers issuing certificates; Part 1: General requirements".
[i.12] ETSI TS 119 411-2: "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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8 ETSI TS 119 421 V1.0.1 (2015-07)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given ETSI TS 119 401 [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 TS 119 401 [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 TS 119 401 [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 TS 119 401 [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
TAI International Atomic Time
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9 ETSI TS 119 421 V1.0.1 (2015-07)
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 TS 119 401 [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 TS 119 401 [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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10 ETSI TS 119 421 V1.0.1 (2015-07)
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 ti
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