| 摘要 |
PROBLEM TO BE SOLVED: To prevent an illegal card forged by copying or the like from being used. SOLUTION: The reader 4 reads out card ID from the fixed information of a prepaid card to be processed and transmits the read card ID to a repeater 3 together with a date information request. The repeater 3 reads out updated date information corresponding to the received card ID from a card information DB and transmits the read information to the reader 4. The reader 4 calculates a number x from the updated date information and a prescribed function and discriminates (deciphers) each data item by regarding a data item in variable information as a data item recorded from data dx. When the deciphered result is appropriate, the reader 4 updates the variable information in accordance with a consumed amount, calculates a new number x from new updated date information indicating the date of the day in accordance with a card ejection request or the like, starts (ciphers) the recording of the updated variable information from the data dx, and transmits the updated date information to the repeater 3. When the deciphered result is unsuitable, the reader 4 executes prescribed error processing. |
