A method for validating a set of payload data by means of said servers. The method includes validating information related to a set of payload data, based on which a check code has been calculated and encrypted by means of an asymmetric cryptographic key pair (A). The encrypted check code (1.11) has been stored at the archive server and associated with a time stamp, which can be used for validation of the set of payload data. The method may enable a selective revocation of certificates that have been used for signing the set of payload data.