| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable an only an authorized playback apparatus to properly play back content by eliminating playback of the content by an unauthorized playback apparatus. <P>SOLUTION: The playback apparatus stores a unique secret key and an ID for each playback apparatus (904), acquires encrypted key information (902, 903), and decrypts the information to acquire key information (905). It is determined whether the key information is key-updating information or a decryption key. If the information is the key-updating information, this is maintained as a source of the secret information. If it is the decryption key, a content key is acquired (910) and descrambled (912) to play back the content (913). The playback apparatus generates a new secret key based on a unique algorithm and the key-updating information for each manufacturer every time it acquires the encryption key information and maintains a secret key in an initial state. <P>COPYRIGHT: (C)2007,JPO&INPIT |
