| 摘要 |
A partial dual encryption encoder, consistent with certain embodiments of the present invention receives video from a source of an unencrypted digital video signal. A first segment of the unencrypted digital video signal is selected for transmission over a first channel. A first encrypter encrypts a second segment of the unencrypted digital video signal under a first encryption method to produce a first encrypted segment and a second encrypter that encrypts the second segment of the unencrypted digital video signal under a second encryption to produce a second encrypted segment. A multiplexer combines the unencrypted digital video signal with the first and second encrypted segments for transmission, so that the first segment is transmitted over a first channel, the first encrypted segment is transmitted over the first channel and the second encrypted segment is transmitted over a second channel. A trigger message generator generates a trigger message indicating that the second encrypted segment of the digital video signal will be encrypted and will be transmitted on a second channel. The multiplexer further combines the trigger message with the first segment, the first encrypted segment and second encrypted segment. |
