| 摘要 |
PROBLEM TO BE SOLVED: To achieve an arbitrary logic gate while concealing both the kind of the gate and input/output value. SOLUTION: An operation x*y of two values x and y is defined as as x*y=x when y=0 and x*y=1-x when y=1, and the logic gate is expressed in a quadratic form function of f<SB>a, b, c, d</SB>(x, y)=a+b*x+c*y+d*(x*y) (a, b, c, d are parameters). Using ciphertexts E(a), E(b), E(c), E(d), E(x), E(y) of a, b, c, d, x, y as an input, E(b*x) is calculated from E(b) and E(x), E(c*y) is calculated from E(c) and E(y), E(x*y) is calculated from E(x) and E(y), and E(d*(x*y)) is calculated from E(d) and E(x*y). E(a+b*x+c*y+d(x*y)) is obtained by adding up E(a), E(b*x), E(c*y), and E(d*(x*y)). COPYRIGHT: (C)2007,JPO&INPIT
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