Qualified timestamp (TSA)
Definition
Frequently asked questions
What is the legal value of a qualified timestamp?
Article 41 of the eIDAS regulation attaches a presumption to it: the date and time it indicates are presumed to be accurate, and the data to which it relates are presumed to be intact. It is up to whoever contests it to provide proof to the contrary. An unqualified timestamp remains admissible as evidence, but without benefiting from this presumption.
How does a timestamp work technically?
The applicant calculates the fingerprint of the document and sends it to the timestamping authority, without transmitting the document itself. The authority associates this fingerprint with a time from a reliable time source, then signs the whole. The token obtained, described by the RFC 3161 standard, proves that this specific content existed at that moment.
What conditions must a timestamp meet to be qualified?
Article 42 of the eIDAS regulation sets out three. It must bind the date and time to the data in such a way as to reasonably exclude any undetectable modification. It must be based on an accurate clock, linked to Coordinated Universal Time. Finally, it must be signed or sealed by a qualified trust service provider.
Why timestamp a document that is already signed?
Because the date carried by a signature comes from the signatory''s device: it is a simple declaration, which nothing guarantees. Timestamping provides a date established by a third party. It makes it possible to demonstrate that the signature was created during the validity period of the certificate, and constitutes the basis of signature formats designed to remain verifiable over the long term.
Related terms
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