| 摘要 |
<P>PROBLEM TO BE SOLVED: To make illegal analysis difficult by a side channel attack and prevent falsification of memory storage values, with respect to the technique of updating a memory of a prepaid card etc. <P>SOLUTION: An authentication apparatus decrypts a management data code text received from the memory device (S303), a head random number is removed therefrom to extract an amount of money (S304). Then, a consumed amount is subtracted to calculate an updated amount as the residual (S305). After random numbers are added to the head of the updated amount as dummy data (S306), the data are encrypted (S307). A result of encryption is written into the prepaid card. It is also effective to employ the encryption system of an encryption block chain mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
