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Time Stamp Qualified Service (TSA)

This guarantees the authenticity and integrity of the time stamp.

An electronic document can incorporate an electronic stamp issued by a Time Stamp Authority (TSA) as is the case of Firmapro, guaranteeing that the moment that document is stamped it is authentic and that the content or form of said document has not been modified.

Moreover, if the issuing service of said time stamp is a qualified service, as regulated by the European eIDAS Regulation, it is the said Authority that guarantees the authenticity of the date and the integrity of the said document at a legal and even civil liability level.

Firmapro, as a Qualified Trusted Services Provider (QTSP) in accordance with eIDAS, and homologated by the Spanish Regulator as it appears in the National Trust Services List (TSL –, issues qualified time stamps from both the Firmapro facilities and from those of the client.

When an electronic document bears a qualified time stamp, all the legislations of the Member States of Europe grant it legal value (no modification since it was stamped) and authenticity of date. In addition, that validity can be verified online in a trusted manner and guaranteed by Firmpro as well as by QTSA.


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This service provides:

Legal Validity

The main value of a time stamp is that it establishes digital evidence of integrity and date with resect to the electronic document. For the purpose of the legislation in force in all the Member States of the EU, a qualified time stamp holds maximum probative value, since the burden of proof is reversed, which now rests on the shoulders of the party that challenges the electronic time stamp provided as proof.

Custody (optional)

The Qualified Time Stamp service contains an optional feature: Firmapro stores and custodies a copy of all digital evidence generated and makes it available to the client if necessary.

How does it work?

Firmapro’s Qualified Time Stamp service is based on the use of the TSP protocol over HTTP, defined in the RFC 3161 standard “Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP)”.

The steps to generate a Time Stamp are as follows:

  1. The client calculates the hash of the document to be stamped.
  2. The client sends a Time Stamp request to a specific Firmapro URL following the RFC 3161 protocol over HTTP, including the hash of the document to be stamped.
  3. Firmapro receives the request, carries out an access control of the client and checks whether the request is complete and correct.
  4. If the result is correct, the TSA signs the petition generating a Time Stamp (including the hash of the document, the date and hour obtained from a reliable source and the electronic signature of the TSA).
  5. The Time Stamp is returned to the client.
  6. The client must validate the Signature of the Stamp and keep it properly.
  7. If the custody service was included in the contract, the TSA will keep a register of the responses generated available to the client for its future verification.

In which cases can we require a Time Stamp service?

  1. Signature of invoices
  2. Publication of official bulletins
  3. Publication of calls to Government Bodies (e.g. Shareholders’ Meetings)
  4. Online signature of contracts
  5. Authentic digital copy (TIS) NOTA del Traductor: Creo que “NTI” es: Technical Interoperability Standard
  6. Certified digitalisation of paper documents.
  7. Re-stamping of electronic documents that have electronic signature for long-term custody.
  8. Stamping of documents that have evidence of electronic identity.
How can we contract this service?

This service can be acquired through annual subscription, either directly accessing via the Internet or through a local infrastructure:

  • Qualified online Time Stamp service on electronic documents (QTSA). It is accessible by our clients via the Internet with RFC 3161 protocol on a secure electronic channel.
  • On-premise service of the Time Stamp Unit (TSU). This is installed in the client’s Data Centre as an appliance managed remotely from Firmapro. The clients who usually request this are those who need to guarantee large volumes or density of electronic stamps.