Method of protecting high definition video signal

• US 6,570,990 B1
• Filed: 11/13/1998
• Issued: 05/27/2003
• Est. Priority Date: 11/13/1998
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Barr, David A., Kohn, Leslie, Le Gall, Didier
• Primary Examiner(s): Darrow, Justin T.
• Application Number:
  US09/192,102
• Time in Patent Office: 1,656 Days
• Field of Search: 380/213, 380/205, 380/200, 380/46, 380/284, 380/281, 380/203, 380/201, 380/214, 380/216, 380/217, 380/218, 380/223, 380/261, 380/268, 348/590, 348/659, 705/57, 713/169
• US Class Current: 380/213
• CPC Class Codes: H04N 11/24 High-definition television systems
• CPC Class Codes: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/4408 involving video stream encryption, e.g. re-encrypting a decrypted video stream for redistribution in a home network
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58
• CPC Class Codes: H04N 7/1696 by changing or reversing the order of active picture signal portions

Abstract

A system controls reproduction of a video transmission between a transmitter and a receiver. The system includes an encryptor with an offset generator adapted to receive the encrypted frame key and to generate a sequence, of pseudo-random values for the color component; and an adder coupled to the offset generator and to the color component signal for providing an encoded color component signal. The system also includes a decryptor with a decryptor offset generator adapted to receive the encrypted frame key and to generate a decryptor pseudo-random value for the color component; and a subtractor coupled to the offset generator and to the color component signal for subtracting the offset signal from the color component signal.

Claims

1. A method for controlling reproduction of video transmission between a transmitter and a receiver, the transmitter and the receiver communicating over a digital interface and a video interface, the video interface having a color component signal, comprising:

communicating an encrypted frame key over the digital interface;

generating a sequence of pseudo-random offsets for the color component signal based on the frame key;

generating an encoded color component signal using one of the pseudo-random offsets; and

transmitting the encoded color component signal over the video interface.

2. The method of claim 1 further comprising seeding a pseudo random number generator with the frame key.

3. The method of claim 1 further comprising:

periodically generating a new frame key; and

initializing a pseudo random number generator with the new frame key.

4. The method of claim 1 further comprising:

scaling the color component signal with a predetermined ratio.

5. The method of claim 1 further comprising clamping the color component signal within a predetermined range.

6. The method of claim 5 wherein the clamping step further comprises:

determining if a value of the color component signal is less than a first value and if so, setting the value of the color component signal to the first value; and

determining if the value of the color component signal is greater than a second value and if so, setting the value of the color component signal to the second value.

7. The method of claim 6 further comprising:

determining whether each pixel is in an encrypted boundary; and

transmitting the pixel unencrypted if the pixel is outside of the encrypted boundary.

8. The method of claim 1 further comprising converting the encoded color component signal to an analog signal.

9. The method of claim 1 further comprising shifting each pixel value in time within a predetermined pixel range.

10. The method of claim 9 wherein the shifting further comprises providing the encoded color component signal to a delay memory.

11. The method of claim 1 further comprising decrypting the encoded color component signal sent over the video interface.

12. The method of claim 11 wherein the decrypting step further comprises:

receiving the encrypted frame key over the digital interface; and

generating the sequence of pseudo-random offsets for the encoded color component signal based on the encrypted frame key.

13. The method of claim 11 further comprising seeding a pseudo random number generator with the frame key.

14. The method of claim 11 further comprising subtracting the pseudo-random offset from the encoded color component signal.

15. The method of claim 14 further comprising compensating for out-of-range values associated with the subtracting step.

16. The method of claim 14 further comprising resealing the color component signal to its original input range.

17. The method of claim 11 further comprising shifting each pixel value within a predetermined pixel range prior to the step of transmitting the encoded color component signal over the video interface.

18. The method of claim 17 further comprising undoing the pixel shift operation using a delay memory.

19. The method of claim 11 further comprising displaying the color component signal after decrypting the encoded color component signal.

20. The method of claim 1 further comprising:

adding the one of the pseudo-random offsets to the color component signal.

21. A method for controlling the reproduction of a video transmission between a transmitter and a receiver, the transmitter and the receiver communicating over a digital interface and a video interface, the video interface having one or more color component signals, comprising:

authenticating the transmitter and the receiver using the digital interface;

periodically transmitting an encrypted frame key to the receiver over the digital interface;

generating a pseudo-random offset at the transmitter for each color component signal during an active part of a scan line;

adding the pseudo-random offset to the color component signal to generate an encoded color component signal;

transmitting the encoded color component signal over the video interface;

generating the pseudo-random offset at the receiver based on the decrypted frame key;

removing the pseudo-random offset from the encoded color component signal transmitted over the video interface to generate a decoded color component signal; and

displaying the decoded color component signal on a display device.

22. A system for controlling the reproduction of video transmission between a transmitter and a receiver, the transmitter and the receiver communicating over a digital interface and a video interface, the digital interface communicating a frame key between the transmitter and the receiver, the video interface having a color component signal, the system comprising:

an encryptor, including;

an offset generator adapted to receive the frame key and to generate a sequence of pseudo-random values for the color component; and

an adder coupled to the offset generator and to the color component signal for providing.an encoded color component signal;

a decryptor, including;

a decryptor offset generator adapted to receive and decrypt the frame key and to generate a decryptor pseudo-random value for the color component signal; and

a subtractor coupled to the decryptor offset generator and to the color component signal for subtracting the decryptor pseudo-random value from the color component signal.

23. The system of claim 22 wherein the color component signal includes one of red, green and blue (RGB) video signals.

24. The system of claim 22 wherein the color component signal includes one of luminance and chrominance video signals.

25. The system of claim 22 wherein the color component signal is a black and white video signal.