| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent leakage of important information by changing the way to encipher a registered user password at each time to reduce the probability that the registered user password is deciphered by the third person as much as possible in the case that a server device preliminarily enciphers and writes the user password of a user who is permitted to use a DB card, and register it when writing a DB file in the DB card. SOLUTION: When writing the DB file in a DB card 3, a server device 1 enciphers the user password with a time variable changing at each time as the key and registers it in the DB card. A portable terminal device 2 acquires the time variable key from the card when accessing the DB card and enciphers a password inputted by an operator by this time variable key to collate the password; and when the operator is an authorized user, the device 2 permits access to the DB file in the card. |
