| 摘要 |
Illegal view and copy protection method in a digital video system for preventing an illegal user from viewing the digital video system and copying therefrom, by setting a descrambling method which decrypts split keystreams adopting a smart card, including a determination step for determining received data of having been scrambled; a reproduction step, if the received data was determined to be scrambled data in the determination step, splitting the scrambled data into a bitstream and a keystream for decrypting the split keystream for reading in key information, and descrambling the split bitstream according to the read in key information for displaying the bitstream on a display; a recording step for, if the received data was determined to be scrambled data in the determination step, recording the scrambled data on a recording medium either as scrambled data of a bitstream and a keystream according to a recording or copying mode, or after splitting the scrambled data into a bitstream and a keystream, encrypting the split keystream, and mixing the encrypted keystream with the bitstream; and a transporting step, if the received data was determined to be scrambled data in the determination step, splitting the scrambled data into a bitstream and a keystream for transporting the split keystream either after decrypting the split keystream with respect to key information from recording side according to a PPC mode or a back-up copy mode, or after decrypting the split keystream two times with respect to key information of its own and key information from recording side; thereby the reproduction step, the recording step and the transporting step can be performed simultaneously or selectively. <IMAGE> |
