| 摘要 |
PROBLEM TO BE SOLVED: To rapidly execute descrambling when a channel is changed-over by permitting a transmitting device to scramble a plurality of channels through the use of common key data, permitting a receiving device to hold common key data and executing descrambling by means of common key data which is held in a key holding means even when any channel is selected. SOLUTION: A key managing device 1.1 generates a work key Kw and stores it in individual information EMM. Then a work key Kw enciphering device 1.2 enciphers individual information EMM through the use of an individual key Kmi which is previously received from the key managing device 1.1 and transmits it to a transport stream TS multiplexing part 1.3 as enciphered individual information EMM. Besides, a scramble key Ks is generated by the device 1.1 and stored in common information ECM. Then a scramble key Ks enciphering part 1.4 enciphers common information ECM through the use of the work key K2 which is previously received from the device 1.1 and transmits it to the Ts multiplexing part 1.3 as common information. |
