| 摘要 |
PROBLEM TO BE SOLVED: To prevent a portable information recording medium from being illegally accessed by checking the validity of each instruction sent from an external device and then executing the instruction. SOLUTION: The portable information recording medium is provided with a random number generating means 1, a certification data generating means 21, an instruction controlling means 3, an instruction executing means 4, a cipher key selecting means 51, and the like. The means 51 is provided with a correspondence table between instructions and cipher keys as a key table and the means 21 is provided with cipher algorithm. The portable information recording medium is an IC card having a microcomputer, an IC card and the like. The means 21 generates certification data for all or a part of an instruction sent from the external device by the use of a random number, a cipher key and the cipher algorithm and the means 3 compares the generated certification data with certification data sent from the external, device together with the instruction to certificate the validity of the instruction and permit the execution of the instruction. |
