Optical disk, an optical disk barcode forming method, an optical disk reproduction apparatus, a marking forming apparatus, a method of forming a laser marking on an optical disk, and a method of manufacturing an optical disk

摘要

An optical disk reproduction apparatus is for use with a disk on which data is recorded. A barcode-like mark is reproduced on the optical disk. It is possible to detect whether an identifier is on the optical disk. A decryption key is obtained from identification information included in the barcode-like mark. When the identifier indicates absence of the barcode-like mark, a signal is generated to indicate that the barcode-like mark is not to be reproduced.