| 摘要 |
According to the invention, on the emitter side, a number generator (10) delivers a random code (XAL) which is sent to the input of a master card (11) which ciphers such code according to a predetermined key (100), the code thus ciphered is broadcast with the video signal, a first device (17) receives on the one hand the random code (XA) and on the other hand the code ciphered by the master card (11) and effects a predetermined numerical combination of these two codes, such combination forming the initialization word of a pseudo-random generator (12) intended to provide a table of codes for scrambling the video signal and, on the receiver side, the ciphered code received is deciphered by a customer card (13), a second device (18) receives at the inputs on the one hand the ciphered code and on the other hand the code deciphered (XA) by the customer card (13) and effects a numerical combination of these two codes which is similar to the combination of the first device (17). |
