OPTICAL DISC CIPHER KEY GENERATING METHOD, CIPHER KEY RECORDING METHOD, CIPHER KEY RECORDING DEVICE, INFORMATION REPRODUCING METHOD, INFORMATION REPRODUCTION PERMITTING METHOD, AND INFORMATION REPRODUCING DEVICE

摘要

PROBLEM TO BE SOLVED: To lower the value of information to be paid by a user and the price of a disk itself, to prevent an illegal copy, and to facilitate the management of cipher key. SOLUTION: A disk reproducing device 2 reads information characteristic of a recording medium 1 where information is recorded for discriminating the recording medium from other recording media out of the recording medium and reads out an arbitrary password code that the user of the recording medium 1 has set, and a software house 3 performs arithmetic process based upon specific algorithm by using the information and password code characteristic of the recording medium 1 to generate a cipher key for reading information out of the recording medium 1. When the user wants to read the information out, the disk reproducing device 2 allows part or the whole of the information recorded on the recording medium 1 to be erased according to a password code which is inputted at this time and the cipher key, which has been generated.