| 摘要 |
PURPOSE:To prevent the leakage and the surreptitious use of a key number, by asking only a person himself that he subjects the key number peculiar to him to a different modification each time and confirming him by the input of the modification result. CONSTITUTION:Only a person himself is asked through a telephone or an earphone that he subjects the key number peculiar to him to a different modification each time, for example, he operates addition, subtraction, multiplication, or division with respect to a certain number of the key number. He inputs the result obtained by subjecting the key number of an asked operation. A processor 5 operates the instructed modifiction and compares the result with contents of the menory of a key file 7 to confirm the key. Thus, others cannot find the process of the modification, and the key number is not leaked even if he operates ten keys in the face of others, and he is confirmed surely. This method is suitable for cash cards of banks and balance check of accounts using telephone. |
