Possibility to incorporate the number of DNI into a card that allows the electronic signature

Without questioning the legal coverage of the utilization of the DNI in relation to the management of the digital certificates of civil servants and public workers, given the principle of quality (art.4 LOPD) they should not discard themselves other options that allow the utilization of the DNI only for the management of the certificate and the electronic signature of documents, if it is proper, and that avoid its posterior diffusion. It would be advisable that the entities of certification that certificates issue that allow the electronic signature on the part of civil servants and public workers bring up a policy of certification that avoids the diffusion of the number of DNI through the utilization of pseudonyms, if these allow the verification of the identity of the person that he signs.