| 摘要 |
PROBLEM TO BE SOLVED: To protect mechanical information stored inside a device, even if the device is stolen or disassembled. SOLUTION: In the key-determining method for, at a transmitting side, encrypting or decrypting a first key used to encrypt data using a plurality of second keys and for, at a receiving side, extracting the second key corresponding to a specific second key included at a receiving side out of the plurality of second keys, a method comprises an input step of inputting first data resulting from encrypting or decrypting the first key using the plurality of second keys; an input step of inputting specific first data encrypted or decrypted by the specific second key in the first data and second data processed to obtain the specific second key, by performing predetermined processing; an extraction step of extracting the specific second key by performing predetermined processing, based on the inputted first and second data; and an output step of outputting the extracted specific second key. COPYRIGHT: (C)2005,JPO&NCIPI
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