摘要:
A user authentication system using a personal identification number, includes a user terminal device for requesting issuance of a personal identification number from an authentication server, storing and displaying a personal identification number, and registering reference information used to permit verification of validity of the personal identification number on the authentication server. Further, the user authentication system includes an inquiry device for requesting verification of validity of the personal identification number from the authentication server, and receiving and displaying results of the verification. Furthermore, the user authentication system includes an authentication server for storing issuance information while issuing the personal identification number, determining whether to permit the verification of the validity of the personal identification number, if the inquiry device requests the verification of the validity, and replying with results of the verification, if it is determined that the verification of the validity is to be permitted.