System and method for protection of video signals

• US 20040083376A1
• Filed: 10/24/2002
• Published: 04/29/2004
• Est. Priority Date: 10/24/2002
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Myers, Robert L.
• Granted Patent: US 7,113,597 B2
• Time in Patent Office: Days
• US Class Current: 713/193
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/4122 additional display device, e.g. video projector digital output for controlling a plurality of local displays G06F3/1423
• CPC Class Codes: H04N 21/4367 Establishing a secure communication between the client and a peripheral device or smart card
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/1696 by changing or reversing the order of active picture signal portions

Abstract

A method and system are provided for protecting an analog video signal sent from a video signal source to a video display enabled to receive a protected video signal. The method includes sending a string of bit values in an encrypted format from the video display to the video signal source. The string of bit values is received in the video signal source and decrypted. The string of bit values is then divided into multi-bit segments in both the video display and the video signal source. A common multi-bit segment in the string of bit values is selected for both the video display and video signal source. A plurality of analog video channels is then sent in a switched order from the video signal source to the video display based on the common multi-bit segment. The plurality of analog video channels is finally decoded in the video display using the common multi-bit segment to decode the switched order.

Claims

1. A method for protecting an analog video signal sent from a video signal source to a video display enabled to receive a protected video signal, comprising the steps of:

sending a string of bit values in an encrypted format from the video display to the video signal source;

receiving the string of bit values in the video signal source and decrypting the string of bit values;

dividing the string of bit values into multi-bit segments in both the video display and the video signal source;

selecting a common multi-bit segment in the string of bit values for both the video display and video signal source;

sending a plurality of analog video channels in a switched order from the video signal source to the video display based on the common multi-bit segment; and

decoding the plurality of analog video channels in the video display using the common multi-bit segment to decode the switched order.

2. A method as in claim 1, further comprising the step of using the common multi-bit value for a selected period of time to switch the order of the plurality of analog video channels.

3. A method as in claim 2, further comprising the step of selecting separate multi-bit values for each time period during which the sending and decoding steps take place.

4. A method as in claim 1, further comprising the step of selecting a separate multi-bit value for each separate video frame.

5. A method as in claim 1, further comprising the step of determining that a video display is enabled to receive the protected signal before sending the protected signal.

6. A method as in claim 5, further comprising the step of determining that the video display is enabled to receive the protected signal by sending an encrypted handshake code.

7. A method as in claim 1, further comprising the step of sending the string of bit values during a vertical sync period.

8. A method as in claim 1, further comprising the step of dividing the string of bit values into 3-bit parts.

9. A method as in claim 1, wherein the step of sending a plurality of analog video channels in a switched order, further comprises the step of sending the plurality of analog video signals in a switched order selected from the group of switched orders consisting of RGB, RBG, GBR, GRB, BRG, and BGR.

10. A method as in claim 9, further comprising the step of defining a switched order that corresponds with a numerical value of each multi-bit segment.

11. A method as in claim 1, wherein the string of bit values is a string of randomly generated bit values.

12. A method as in claim 11, wherein the string of bit values has pre-determined length.

13. A method as in claim 1, wherein the analog video signal is sent directly from the analog video signal source to an analog video display.

14. A device for protecting a video signal, comprising:

a string generator configured to generate a bit string;

an encryption module in communication with the string generator to encrypt the bit string;

a video display, in communication with the encryption module, configured to transmit the encrypted bit string received from the encryption module and to receive a video signal;

a video signal source configured to receive the encrypted bit string and to transmit the video signal to the video display via a plurality of video channels;

a decryption module, in the video signal source, configured to decrypt the bit string received by the video signal source and to divide the bit string into multi-bit segments; and

wherein the video signal source uses the multi-bit segment to transmit the video signal in a scrambled pattern to the video display and the video display uses the same multi-bit pattern to descramble the video signal for display.

15. A device as in claim 14, wherein the bit string is a pre-determined length.

16. A device as in claim 14, further comprising a crosspoint switch configured to be used to scramble or descramble the video signal for the display.

17. A device as in claim 14, further comprising a synchronized multi-bit segment selector contained within the video signal source and the video display to select a multi-bit pattern of a selected length within the bit string.

18. A device as in claim 14, further comprising a challenge message that is sent to the video display from the video signal source.

19. A device as in claim 18, further comprising a response message that is sent to the video signal source from the video display in reply to the challenge message to verify the video display can receive a scrambled video signal.

20. A method for protecting a video signal sent from a video signal source to a video display, comprising the steps of:

sending a random string of bit values in an encrypted format from the video display to the video signal source;

decrypting the random string of bit values when the random string is received in the video signal source;

dividing the random string of bit values into 3-bit segments in both the video display and the video signal source;

selecting a common 3-bit segment in the random string that has not been used yet, for both the video display and video signal source;

sending three channels of a video signal in a scrambled order from the video signal source to the video display based on a value of the common 3-bit segment; and

decoding the three channels of the video signal in the video display using the common 3-bit segment.

21. A method as in claim 20, further comprising the step of using at least a 48-bit value as the random string of bit values.

22. A method as in claim 20, further comprising the step of associating each integer value for the 3-bit values with the scrambled formats comprising RGB, RBG, GBR, GRB, BRG, and BGR.

23. A method as in claim 20, further comprising the steps of:

sending an encrypted challenge string from the video signal source to the video display;

decrypting the challenge string in the video display; and

sending the decrypted challenge string back to the video signal source as a response to verify that the video display can receive a scrambled video signal.