| 摘要 |
PURPOSE:To obtain an IC card to be used such as a credit card without lowering the security by adopting the constitution such that the decrease in the monetary amount in the purchase price storage area is attained only after a key by an issuing person is collated and the readout of the monetary amount and the increase in the monetary mount are attained without requiring the collation of the key of the issuing person. CONSTITUTION:A party issuing the card uses a terminal equipment having an issuing person key to write information not to be utilized for other parties than the issuing party into a secret area 11 and the monetary amount '0' is written in a purchase price storage area 12. Since the work is an operation to rewrite while the data of the purchase price storage area 12 is decremented, it is executable by the terminal equipment of the issuing party only having the issuing person key. Then every time the IC card possessor uses the IC card for purchasing, the purchased price is incremented in the purchase price storage area 12. Since this work is an operation to rewrite the data while the content of the purchase price storage area 12 is incremented, no collation by the issuing person key is required.
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