| 摘要 |
PROBLEM TO BE SOLVED: To repeatedly use a prepaid card by preliminarily recording initial information in a plurality of blocks and performing special information processing by a card processor when used. SOLUTION: In a recorder 2, the memory of an IC card is divided into (n) blocks, amount information is recorded in each block, each block is enciphered by a cryptographic key except the first block, and further, all of the blocks are enciphered by a common cryptographic key to prepare an initial IC card 3. A service providing facility 4 inserts the card 3 into a reader 6, and an equivalent such as purchased merchandise is offset from the amount information of the first block by using the common cryptographic key. A balance is enciphered again by the common cryptographic key. When an IC card 7 whose balance becomes zero together with cash 8 are inserted into a money receiving machine 9, the amount information of the next block is decoded by the cryptographic key proper to the block and a usable recycled IC card 10 is discharged. |
