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...http://www.google.com/patents/US7242773?utm_source=gb-gplus-sharePatent US7242773 - Multiple partial encryption using retuning
