Method and apparatus for preventing illegal copy or illegal installation of information of optical recording medium

摘要

A recording and reproducing system for performing the reproduction using an optical recording medium. A physical feature of a ROM type disk is extracted and enciphered before being recorded in an optical disk. The cipher reproduced and converted into a plain text physical feature, which in turn, is compared with the physical feature information detected from the ROM disk. When both are coincident with each other, the operation of the system stops, thereby preventing the use of an illegally duplicated disk. The physical feature information, recorded on a magnetic recording layer 4 of the optical recording medium 2, is reproduced by an optical head 8 and compared with the information measured by a physical feature information detector, thereby detecting a duplicated medium.