| 摘要 |
PROBLEM TO BE SOLVED: To provide technology capable of computing inversion of a finite field without generating inside variable buffer overflow concerning an inverse computing device computing the inversion of the finite field. SOLUTION: In the inverse computing device 10, an input part 11 sets intermediate variables (A), B,α,βby inputting a value X for obtaining inversion and a modulus P of the finite field. A conditional intermediate variable exchange part 13 exchanges values between A-B and betweenα-β, and performs subtraction processing between A-B and betweenα-βin according to conditions. A modulus sign adjustment part 14 sets-P or P to an intermediate variable P' according to positive or negative ofα. A conditional modulus addition shift part 15 adds P' toαand makes the values of (A) andαhalves whenαis odd. A conversion completion determination part 16 determines completion of processing by an intermediate variable conversion part 12 if the value of (A) is 1. An intermediate variable sign adjustment part 17 adds P toαwhenαis negative. An output part 18 outputs the final value ofαas obtained inversion. COPYRIGHT: (C)2010,JPO&INPIT
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