Secure coding and decoding system and method for television program signals

Apparatus for decoding an encoded video signal having parts thereof that are rearranged relative to other parts, comprising:

• means for receiving the encoded video signal;
• a plurality of analog delay elements connected in series to receive successive parts of the received signal;
• switching means for selecting a delayed output signal from one of the delay elements;
• means for controlling said switching means to select the output signal from a predetermined one of said delay elements in a first mode and to sequentially select the output signal from each of the delay elements in a cyclic fashion in a second mode;
• and
• means for receiving the selected output signals from the switching means as a decoded video signal.

A method for enabling only authorized television receivers to display a television program in an intelligible manner, comprising the steps of:

• generating a television program signal;
• generating a pseudo-random binary signal at an encoding station;
• alternately arranging parts of the program signal relative to one another in one of two predetermined orders in accordance with the binary signal, to thereby form an encoded program signal;
• transmitting the encoded program signal and a status signal relating to the generation of the binary signal at the encoding station;
• storing successive parts of the transmitted signal at an authorized receiver;
• independently generating the pseudo-random binary signal at the receiver;
• synchronizing the independent generation of the pseudo-random binary signals by initializing the generation of binary signal at the receiver in accordance with the status signal and initiating generation of the binary signal upon receipt of a predetermined portion of the transmitted signal;
• sequentially retrieving the stored parts of the signal;
• selectively altering the order of retrieval in accordance with the binary state of the pseudo-random binary signal, to thereby form a decoded video signal;
• and
• applying the decoded video signal to the authorized receiver for display.

A method for enabling only authorized television receivers to display a television program in an intelligible manner, comprising the steps of:

• generating a television program signal;
• generating a psuedo-random signal at an encoding station;
• encrypting said television program signal in accordance with said psuedo-random signal;
• producing a control signal indicative of a parameter in the generation of said psuedo-random signal at a predetermined time;
• transmitting the encrypted television program signal to a receiver station;
• transmitting said control signal with said program signal;
• providing a decode control key to the receiver station;
• utilizing said decode control key and said transmitted control signal to generate a psuedo-random signal at said receiver station;
• decoding the encrypted television program signal in accordance with the psuedo-random signal generated at said receiver station;
• and
• applying the decoded program signal to a receiver for display.