| 摘要 |
Copyright protection information, which is recorded on an optical recording medium, is made not to be easily cracked, so that the profits of copyright owners are protected. Signals based on a plurality of sequences obtained by scrambling copyright protection information SA by using a plurality of binary sequences are recorded in a predetermined area of an optical recording medium ( 2 ). Since the copyright protection information SA cannot be decrypted as long as the plurality of binary sequences used for scrambling are not known, an encryption process can be performed by using the information as a key. Furthermore, during playback, the copyright protection information SA is decrypted by performing a correlation computation with the played back signal by using a plurality of binary sequences, which are the same as those used for scrambling the data during the recording of the copyright protection information SA. Then, the encryption performed on the recorded information is unscrambled using the information.
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