PREPAID CARD SYSTEM, READER AND PASSWORD TRANSACTION METHOD

摘要

PROBLEM TO BE SOLVED: To precisely detect a prepaid card medium altered or forged by the copying of storage information and to inhibit the use of it. SOLUTION: A distance measuring part 145 reads fixed information by a magnetic head 143, measures a distance from a card edge to a fixed information end part and generates a peculiar password key K. A ciphering processing part 144 executes deciphering/ciphering by using the peculiar password key K obtained by the distance measuring part 145 at the read/write of variable information on amount information of a prepaid card by a data reading part 142 through the magnetic head 143. The ciphering processing part 144 deciphers storage information by using peculiar password key K obtained by the distance measuring part 145 at when the prepaid card is inserted. When the information which is read by the peculiar password key K through the data reading part 142 is not precisely decoded, an illegal prepaid card is detected to be inserted and abnormality is detected.