| 摘要 |
PROBLEM TO BE SOLVED: To provide a system, which prevents a card from being wrongfully used by another person, and a card for this system. SOLUTION: At least one of a pair of mediums communicating with each other is an IC card, and the signal transmitted from the other medium is received by a reception part 101 of the IC card, and the reception signal level of the signal received by the reception part 101 is discriminated by a reception level discrimination circuit 102. When this reception level is equal to or higher than a certain level, a collation circuit 103 collates the reception signal against a password in a reception password storage part 106; and if they coincide, a gate 107 is opened to make a CPU 113 of the IC card accessible from the outside, and the IC card can be used. If they do not coincide with each other or the signal can be received but has a certain level or lower or any signal is not received, the gate 107 is closed so that the IC card cannot be used. |
