Electronic Timestamping: Definition and Usage

Electronic Timestamping in a Nutshell

Electronic timestamping (timestamping) links a digital document to a precise date and time in a verifiable and tamper-proof manner. It is proof that a document existed at a specific moment — a decisive argument in case of dispute over the date of a commitment.

Why Timestamping is Critical

Without timestamping, it is impossible to prove:

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

• who modified the document last

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

For a contract worth €50,000 signed on 30 December: 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 entire package 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 attention:

• Calls for tenders (submission deadline)

• Intellectual property (creation date)

• High-stakes contracts (fiscal year)

• Share transfers (transfer date)

• Regulatory filings (CNIL, ACPR, AMF)

Proof of Existence and Integrity

Timestamping proves two things:

• Existence: the document existed at date 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 include timestamping in PAdES format. For cases requiring qualified timestamping, we interface with European eIDAS-qualified TSAs.

FAQ

Is a system timestamp sufficient?

No. A local timestamp can be modified. 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 the 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 prior art).

Conclusion

Timestamping is the safety belt of electronic signature: invisible in daily use, essential in case of accident.

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