Cryptographic proof that stands the test of time

ADSS TSA Server is an RFC 3161-compliant timestamping authority (TSA) built for trust service providers, qualified trust service providers (QTSPs), Enterprises and Governments to deliver timestamp services as part of digital signing workflows. It provides cryptographically signed proof that a digital asset — document, signature, transaction, or software artefact — existed at a specific point in time and has remained unchanged since.

As part of the Ascertia Digital Trust Platform, ADSS TSA Server supports eIDAS compliance, long-term validation (LTV), and the preservation of legal evidential value long after signing certificates expire or cryptographic standards evolve — making it the natural choice for TSPs and QTSPs operating under regulatory and audit obligations.

  • RFC 3161-compliant trusted timestamping authority
  • Trusted timestamps for digital signatures, code signing, and electronic records
  • High-performance, high-availability deployments
  • Audit-grade digital evidence for compliance and legal assurance
  • ETSI and eIDAS-aligned timestamping support
  • Designed to support evolving cryptographic standards, including migration strategies towards post-quantum cryptography (PQC)
ADSS TSA Server Illustration

In many digital processes, electronic signatures alone are not enough for long-term validation. Certificates expire, keys are revoked, and cryptographic algorithms evolve over time.

Trusted timestamping provides independent, cryptographically verifiable proof that data existed at a specific moment. This helps ensure that digital signatures, transactions, and records remain trustworthy, auditable, and legally defensible over the long term.

Unlike standard system timestamps, trusted timestamps are independently signed by a cryptographic timestamp authority and can be verified long after creation.

ADSS TSA Server helps protect organisations from disputes, compliance failures, and long-term validation risks.

ADSS TSA Server is built for environments where digital trust must remain provable, auditable, and verifiable for years or decades.

It supports current cryptographic standards and aligns with Ascertia's future-ready PKI strategy, helping organisations maintain long-term cryptographic trust as standards evolve, including the transition towards PQC.

This makes it ideal for regulated industries, government services, financial systems, healthcare, legal workflows and legally binding digital transactions.

Unlike basic timestamping services, ADSS TSA Server is designed for large-scale PKI environments requiring both high availability, policy-based controls, HSM-backed signing keys, and long-term cryptographic trust.

Common trusted timestamping use cases

  • Long-term validation (LTV) of digital signatures
  • Qualified and eIDAS-compliant electronic transactions
  • Code signing timestamps and software integrity verification
  • Financial transaction evidence and audit trails
  • Digital document archiving and records management
  • Government and regulated industry workflows
  • Non-repudiation and digital evidence preservation

ADSS TSA Server is engineered for high-volume, mission-critical timestamping services:

  • High-throughput timestamp generation supporting large transaction volumes
  • Active-active clustering and load-balanced architectures
  • Resilient integration with trusted time sources
  • 24/7 operation for Trust Service Provider, Enterprise, and Government deployments
  • Scalable deployment architectures for growing digital trust environments

ADSS TSA Server provides fine-grained policy and operational control:

  • Multiple timestamping policies for different applications and use cases
  • Secure signing of timestamps using HSM-protected keys
  • Role-based administrative access
  • Strong separation of duties for compliance and audit
  • Configurable operational controls supporting regulated environments

ADSS TSA Server supports flexible deployment models:

  • On-premise, virtualised, and private cloud, and hybrid cloud environments
  • Integration with Hardware Security Modules (HSMs)
  • Support for trusted time sources and secure time synchronisation
  • Support for resilient, high-availability deployment architectures

Monitoring, Audit, and Standards Compliance

Operational visibility and evidence are essential for trusted timestamping services, delivered in line with international standards and regulatory requirements.

ADSS TSA Server includes:

Comprehensive logging of timestamp requests and responses

Monitoring of service health, availability, and performance

Detailed reporting for audit, compliance, and investigations

Long-term evidence records supporting legal and regulatory requirements

Audit-ready records for compliance and forensic analysis

ADSS TSA Server is designed to meet international standards and regulatory requirements, including:

RFC 3161 and related IETF timestamping standards

ETSI and eIDAS-aligned timestamping profiles

Support for qualified and regulated timestamping deployments

Interoperability with new and existing PKI and digital signature ecosystems

ADSS TSA Server operates as a core timestamping and validation service within the Ascertia PKI platform.

It complements certificate issuance and revocation services by anchoring trust in time, supporting long-term validation (LTV) of digital signatures and electronic records across their full lifecycle.

Together with Ascertia PKI, ADSS OCSP Server, and validation services, ADSS TSA Server enables end-to-end digital trust services across identity, signing, validation, and time assurance.

ADSS TSA Server integrates seamlessly into existing PKI ecosystems.

It supports industry-standard timestamp clients and workflows, including electronic document signing, code signing, transaction processing, digital archival systems and long-term validation services.

APIs and standards-based protocols enable integration with business applications, trust services, and digital workflows.

Common deployment models include:

  • High-availability, single-site TSA cluster
  • Active-active multi-site deployment for resilience
  • Segmented architectures with protected signing environments

Each model is designed to ensure continuous availability, operational resilience, and verifiable digital trust.

ADSS TSA Server works seamlessly with:

  • Ascertia PKI
  • ADSS OCSP Server
  • Digital signature services
  • Validation and long-term archival services

Together, these components deliver end-to-end digital trust across identities, transactions, signatures, validation, and time assurance.

Next steps

  • View reference architectures
  • Speak to a digital trust specialist
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FAQs

Timestamping provides trusted evidence that digital data, such as a document or digital signature, existed at a specific date and time. A Time Stamping Authority (TSA) creates a digitally signed timestamp. that can be independently verified, helping organisations prove data existed and detect whether it has subsequently been changed.

ADSS TSA Server receives a cryptographic hash of the data and returns a signed timestamp token linking it to a specific date and time. This allows applications to verify the evidence and detect changes to the timestamped data, without sending the original document to the server.

Long-term validation (LTV) allows digital signature to remain verifiable after the signing certificate has expired or the supporting validation services are no longer available. It works by preserving important verification evidence including certificates, certificate revocation information and trusted timestamps.

ADSS TSA Server provides the trusted timestamps that form part of the evidence needed in long-term signature validation (LTV). Combined with certificates and revocation evidence, these timestamps help establish whether a signature was valid at the relevant time, even after the signing certificate has expired. Long-term validation also requires preservation of this evidence.

Yes, ADSS TSA Server can be deployed on-premise or as part of a cloud service, giving organisations flexibility to meet their security and operational requirements. It supports Windows and Linux environments, with database and hardware security module (HSM) integration options.

ADSS TSA Server is designed for high-volume timestamping and can generate thousands of timestamps per second. Multiple servers can operate together in a load-balanced environment to support growing demand and high availability. A single instance can also host multiple TSA profiles, each with its own timestamping policy and signing keys.

ADSS TSA Server supports industry standards including RFC 3161 and RFC 5816 timestamping, as well as Microsoft Authenticode. It works with compatible applications, including Adobe Acrobat and Microsoft Office, enabling timestamping within document signing, software signing, and other digital workflows.

Yes, ADSS TSA Server provides the technology needed to support qualified electronic timestamping services under the EU's eIDAS regulation. When issued by an authorised Qualified Trust Service Provider (QTSP) as part of a qualified timestamping service, these timestamps benefit from a legal presumption that their date and time are accurate, and the integrity of the associated data. The provider and its timestamping service must hold qualified status, as reflected in the relevant national trusted list.