Electronic Timestamping: Definition and Usage

Electronic Timestamping in a Word

Electronic timestamping links a digital document to a precise date and time in a verifiable and tamper-proof way. It is proof that a document existed at a given moment — a decisive argument in case of a dispute over the date of an agreement.

Why Timestamping is Crucial

Without timestamping, it is impossible to prove:

• whether a contract was signed before or after a key event

• who last modified the document

• whether the date written in the document matches the actual signature

For a 50,000 € contract signed on December 30th: in the current or next fiscal year?

How Timestamping Works

The standard process relies on a third-party timestamping authority (TSA) that:

• Receives the cryptographic fingerprint of the document

• Adds the precise date and time (NTP clock)

• Signs the whole with its own key

• Returns a timestamp token

This token is embedded in the PDF in PAdES format. Anyone can then verify the date and integrity.

Simple vs Qualified Timestamping

eIDAS distinguishes two levels:

• Simple: any service provider. Useful proof but without legal presumption.

• Qualified: QTSP listed on the trust list. Legal presumption of reliability (article 41 eIDAS).

For high-value documents, qualified timestamping is recommended.

When to Use Timestamping

Timestamping is systematic in modern electronic signatures. But certain situations require particular vigilance:

• Calls for tenders (submission deadline)

• Intellectual property (creation date)

• High-stakes contracts from a tax perspective (accounting period)

• Share transfers (transfer date)

• Regulatory filings (CNIL, ACPR, AMF)

Proof of Existence and Integrity

Timestamping proves two things:

• Existence: the document existed at time T

• Integrity: no modifications since T

How to Verify a Timestamp

Adobe Reader → signature properties → timestamp authority details. Displays TSA name, exact date, validity status. Tools like pdfsig allow command-line verification.

How Certyneo Helps You

All Certyneo signatures embed a timestamp in PAdES format. For cases requiring qualified timestamping, we interface with eIDAS-qualified European TSAs.

FAQ

Is a system timestamp enough?

No. A local timestamp can be altered. Only a trusted third party has probative value.

Do I have to pay for qualified timestamping?

Generally included in professional plans of signature platforms.

Does timestamping expire?

The token does not expire, but its long-term validity depends on algorithms. Use PAdES-LTA for multi-decade validity.

Does timestamping replace signature?

No. Signature identifies the author, timestamping proves the moment. They are complementary.

Can I timestamp without signing?

Yes, to prove existence on a date (digital INPI filing, proof of priority).

Conclusion

Timestamping is the safety belt of electronic signature: invisible day-to-day, essential in case of an accident.

Try Certyneo to send, sign and track your documents online simply, quickly and securely.