| 摘要 |
Data C generated by scrambling user-desired digital data P and a control word CW<SUB>p </SUB>corresponding to the number of reproductions p are recorded on recording media. When creating a master, a user has already been charged for the number of reproductions p. A decryption block decrypts the control word CW<SUB>p</SUB>, which is read from the recording media, to CW<SUB>0</SUB>. A de-scrambler uses the decryption control word CW<SUB>0 </SUB>to decrypt the digital data P for output to a reproduction unit. After confirming the end of reproduction, the decryption block writes a control word CW<SUB>(p-1) </SUB>back to the recording media. The recording media may be reproduced p times with no need for communication between a reproduction device and an accounting manager. |
