10 Electronic Signature
10.4 Time stamp

A time stamp (or timestamp) demonstrates the existence of a document in a given form at a given (specific) time; it does not deal with when the document was created and who owned the document.

The time stamp's data structure is similar to the structure of certificates. Technically, a time stamp is implemented as just another electronic signature derived from the TSA (Time Stamp Authority).

There is also a so-called qualified time stamp as the equivalent of a qualified electronic seal or qualified electronic signature. Qualified time stamp is created by a qualified time stamp service provider.

The electronically signed structure of a time stamp includes, among many others:

- name of the publisher,
- unique stamp’s serial number,
- HASH (checksum) derived from document
- time

TSA, time stamp authority, proves synchronization of its time source with UTC (Universal Time Coordinated).

Time stamp example