Electronic Timestamping: Definition and Usage

Electronic Timestamping in a Nutshell

Electronic timestamping links a digital document to a precise date and time in a verifiable and tamper-proof manner. It's 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's 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 30 December: in the current or following financial year?

How Timestamping Works

The standard process relies on a timestamp authority (TSA) that:

• Receives the cryptographic fingerprint of the document

• Adds the precise date and time (NTP clock)

• Signs the whole thing 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 registered 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 signature. But certain situations require particular attention:

• Tenders (submission deadline)

• Intellectual property (creation date)

• High-value contracts (financial year implications)

• Share transfers (transfer date)

• Regulatory filings (CNIL, ACPR, AMF)

Proof of Existence and Integrity

Timestamping proves two things:

• Existence: the document existed on date T

• Integrity: no modification since T

How to Verify a Timestamp

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

How Certyneo Helps You

All Certyneo signatures embed timestamping 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 modified. Only a trusted third party has probative value.

Do You Have to Pay for Qualified Timestamping?

Generally included in professional plans of signature platforms.

Does Timestamping Expire?

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

Does Timestamping Replace a Signature?

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

Can I Timestamp Without Signing?

Yes, to prove existence at a given date (digital INPI filing, proof of anteriority).

Conclusion

Timestamping is the seatbelt of electronic signature: invisible in everyday use, essential in case of trouble.

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