When is it advisable to use time-stamps?

The time-stamp endorses the existence of data before a specific date and it is essential for non-repudiation. The time-stamp of an electronic signature (ETSI ES-T) verifies that it existed before a certain date and that it was generated during the digital certificates’ validity period (for example, that it has not been signed after the certificate’s revocation date).

Furthermore, to preserve an electronic signature over long periods of time, beyond the digital certificate’s validity period, proof of the existence of certificate status data (CRLs or OCSP) will be required at the time of signing. To do so, the electronic evidence will be filed together with the temporarily stamped signatures, according to what is specified in the ETSI ES-A file signature format.

TrustedX supports the signature profiles defined by the ETSI XAdES and CAdES standards: basic signature (BES), explicit policy signature (EPES), signature with time-stamp (ES-T), complete signature (ES-C) and file signature (ES-A). The time-stamp format supported by TrustedX is IETF TSP (RFC 3161 Internet X.509 Public Key Infrastructure. Time-Stamp Protocol).