| 摘要 |
PROBLEM TO BE SOLVED: To simplify the management of a cipher key to improve the operability while preventing wrong use and wrong copy of information. SOLUTION: A cipher key is generated based on a discrimination statement set by a user. The cipher key is recorded in a low-density recording area of an optical disk. At the time of reproducing, the cipher key is read out from the low-density recording area of the optical disk, and the discrimination statement is obtained from this cipher key (S1). The user inputs a discrimination statement in accordance with a discrimination statement input request (SJ). Then, this inputted discrimination statement and the discrimination statement obtained from the cipher key are compared with each other (SK). If they coincide with each other (Y in SL), information designated by the cipher key out of main information recorded on the optical disk is reproduced (SM). The same discrimination statement can be set for plural optical disks different by cipher keys, thus simplifying management. |
