INVERSE COMPUTING DEVICE AND INVERSE COMPUTING PROGRAM

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, β by 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 between α-β, and performs subtraction processing between A-B and between α-β in according to conditions. A modulus sign adjustment part 14 sets-P or P to an intermediate variable P' according to positive or negative of α. A conditional modulus addition shift part 15 adds P' to α and makes the values of (A) and α halves when α is 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 to α when α is negative. An output part 18 outputs the final value of α as obtained inversion.;COPYRIGHT: (C)2010,JPO&INPIT