USER AUTHENTICATION DEVICE

PROBLEM TO BE SOLVED: To manage the right of access of an individual user indirectly by way of a manager X. SOLUTION: When there is an access to a server device 200 from a user A, the authentication is performed by an access authentication part 110. The authentication succeeds when a user ID and a password coincide with registered contents of a user information registration part 120 and a period of validity has not passed. When the period of validity has passed, a user is urged to input a key of period extension. When the key of period extension inputted at this time coincides with a key stored in a period extending key storage part 130 and a new period of validity after extension has not passed, the authentication succeeds. Period extending keys α1, α2, and α3 are issued by a period extending key issuing part 140 during a specified time, are stored in the period extending key storage part 130, and are transmitted to the manager X. The manager X arbitrarily decides whether or not the period extending keys should be communicated to individual users A, B, and C. COPYRIGHT: (C)2004,JPO&NCIPI