US 6,983,050 B1
Methods and apparatus for protecting information content
Yacov Yacobi, Mercer Island, Wash. (US); Paul England, Bellevue, Wash. (US); and Gideon A. Yuval, Mercer Island, Wash. (US)
Assigned to Microsoft Corporation, Redmond, Wash. (US)
Filed on Jun. 30, 2000, as Appl. No. 9/609,019.
Claims priority of provisional application 60/160603, filed on Oct. 20, 1999.
Int. Cl. H04N 7/167 (2006.01); H04B 1/69 (2006.01)
U.S. Cl. 380—210 14 Claims
OG exemplary drawing
 
1. 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+c1B
G′=a2R+b2G+c2B
B′=a3R+b3G+c3B
wherein the matrix coefficients are generated such that each of the R′, G′ and B′ signals will be the product of summing two signals in the set of analog signals R, G, B and subtracting one of the signals in the set of analog signals R, G, B.