| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable an only an authorized playback apparatus to play back content by eliminating playback of the content by an unauthorized playback apparatus. <P>SOLUTION: The playback apparatus stores unique keys and IDs for each playback apparatus, production lot, apparatus type or manufacturer (904) acquires encrypted key information (902, 903), and decrypts the encrypted key information using a secret key to acquire the key information (905). The playback apparatus determines whether the key information is key-updating information to be used for updating based on the leakage of the secret key or a decryption key used for decrypting a content key, based on an identifier added to the key information. If the key information is the key-updating information, a new secret key is generated based on an algorithm unique for each manufacturer incorporated in the playback apparatus and the key-updating information (914). If the key information is the decryption key, a content key is acquired (910) and descrambles the acquired content key (912) to play back the content (913). The playback apparatus stores a newest secret key and an initial secret key. <P>COPYRIGHT: (C)2007,JPO&INPIT |
