Methods and apparatus for protecting information content
First Claim
1. A method of processing first, second and third signals for use in a system having first, second, and third signal lines, comprising:
- generating, using a pseudo-random number generator, pseudo-random output values; and
changing, as a function of at least one of said pseudo-random output values, which ones of the first, second, and third signal lines are used to transmit the first, second and third signals.
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Accused Products
Abstract
Methods and apparatus for protecting copyrighted information, e.g., video signals, from unauthorized copying. Analog red (R), green (G) and blue (B) video signals are transmitted from a source device, e.g., a display adapter, to a display device, e.g., a monitor, over corresponding analog signal lines after the identify of the destination device is confirmed by receipt of a certificate assigned to the destination device. A session key, used for encrypting the analog signals, is generated and exchanged between the source and destination devices after the identification of the destination device is confirmed. The source and destination devices each includes a pseudo-random number generator driven by the session key. The lines that carry the R, G and B video signals are changed, e.g., swapped, on a periodic basis as a function of the output of the pseudo-random number generator in the source device. The destination device, which has an input to its pseudo-random number generator synchronized with the random number generator of the source device, decrypts the received video signals in a complimentary fashion to the encryption. Encrypted digital information subject to copying constraints may be supplied to a display adapter via an IEEE 1394 compliant bus.
241 Citations
55 Claims
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1. A method of processing first, second and third signals for use in a system having first, second, and third signal lines, comprising:
-
generating, using a pseudo-random number generator, pseudo-random output values; and
changing, as a function of at least one of said pseudo-random output values, which ones of the first, second, and third signal lines are used to transmit the first, second and third signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of generating encrypted analog first, second and third signals (R′
- , G′
, B′
, respectively) from first, second, and third analog input signals (R, G, B, respectively) the method comprising;
pseudo-randomly generating at least one of a plurality of matrix coefficients, a1, a2, a3, b1, b2 b3, c1, c2, c3;
using an encryption circuit to perform a matrix multiplication operation to generate the encrypted analog first, second, and third signals, according to the following equations; R′
=a1R+b1G+c1BG′
=a2R+b2G+c2BB′
=a3R+b3G+c3B. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27)
- , G′
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25. A communication method comprising the steps of:
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using a pseudo-random number generator to generate output values; and
modifying first, second and third signals, by performing a matrix multiplication operation thereon utilizing matrix coefficients which are a function of at least one of the pseudo-random output values, the modified first, second and third signals being encrypted analog signals so as to define first, second and third encrypted analog signals; and
transmitting the first, second and third encrypted analog signals to a destination device. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34)
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35. A computer readable medium comprising:
computer executable instructions for controlling a computer device to perform the steps of;
operating a pseudo-random number generator to generate a pseudo-random output value; and
modifying first, second and third signals, by performing a matrix multiplication operation thereon utilizing matrix coefficients at least one of which is a function of the pseudo-random number output value so as to define first, second and third encrypted analog signals; and
transmitting the first, second and third encrypted analog signals to a destination device.
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36. A device, comprising:
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a video signal encryption circuit for encrypting, in response to a pseudo-random number, red, green and blue video signals and for producing first, second and third analog encrypted video signals;
a pseudo-random number generator circuit, coupled to the video signal encryption circuit, for producing the pseudo-random number value; and
an input/output interface for outputting the first, second and third encrypted analog video signals. - View Dependent Claims (37, 38, 39, 40)
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41. A method of decrypting encrypted analog signals including the steps of:
generating a first decrypted analog signal from a first pair of encrypted analog signals by;
summing the two encrypted analog signals in the first pair of analog signals to produce a first sum; and
dividing the first sum by a first value to produce a first decrypted analog signal. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A method of generating an encrypted analog signal from at least two of a first analog input signal, a second analog input signal, and a third analog input signal, the method comprising:
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pseudo-randomly generating an encryption value;
multiplying a first one of said first, second, and third analog input signals with said encryption value to produce a multiplied signal; and
combining said multiplied signal with at least a second signal generated from a second one of said first, second, and third analog input signals to produce said encrypted analog signal. - View Dependent Claims (54, 55)
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Specification