| 摘要 |
PURPOSE:To prevent interception by scrambling 1st and 2nd data in a hierarchical way so as to decode them entirely. CONSTITUTION:Scrambling using a key signal K1 is applied to a common information signals string and scrambling by using key signals K1, K2 is implemented to an indivisual information signal string. A key signal K2 scrambling an individual information signal string is inserted to a common information signal string and the common information signal string is scrambled by the key signal K1 and sent. The common information signal string is descrambled at a receiver side and the key signal K2 is extracted from the common information signal string, the individual information signal string is descrambled by using the key signal K2 and the substantial descrambling is implemented for the reception signal. Thus, the decoding is much made difficult. |
