| 摘要 |
<p>In a recording/reproducing apparatus in which reproduction of information is carried out by using an optical recording medium, the physical characteristics of a ROM disk are extracted and enciphered, and the resultant ciphers are recorded on the optical disk. In order to reproduce the information, the physical characteristics obtained by deciphering these ciphers and physical characteristics information detected from the ROM disk are compared with each other. When they do not agree, the use of an illegally duplicated disk is inhibited by stopping the operation of the apparatus. A duplicated medium is detected by reproducing the physical characteristics information, which have been recorded in a magnetic recording layer (4) in an optical recording medium (2), by a magnetic head (8), and comparing this reproduced information with the information determined by a physical characteristics information detecting means.</p> |
