| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that the prevention of copying to other optical disks without permission by the user of a reproducing device is impossible in the copy preventing method using written promise, password or key. SOLUTION: At the mastering process 1, two key reading flags are recorded on a straight line passing a rotational center of the optical disk, and at the key information detecting process 2, each information in the preset track range is taken out among informations of each track positioned on the straight line connecting these flags and detected as reproduction permitting intrinsic information to the optical disk. This reproduction permitting information is converted into codes and distributed with the optical disk as the key information. This key information is inputted to the reproducing device by the user and comparatively collated with the reproduction key information reproduced from the optical disk (steps 6, 7). The reproduction is permitted only when both of them coincide with each other. |
