SECURE COMPUTATION METHOD, SECURE COMPUTATION SYSTEM, RANDOM SUBSTITUTION DEVICE, AND PROGRAM

摘要

The purpose of the present invention is to carry out secure computation that includes secure random substitution at high speed. In a unit substitution step (S12), random substitution devices (p0, … , pk-1) make substitution of an additive secure dispersion value (<>ρi) for plain text (a) using substitution data (π) sub share (πρi). In a redispersion step (S14) the random substitution device (p0) generates an additive secure dispersion value (<>ρi+1 pk) using random numbers (r1, …, rk-1) shared with each of random substitution devices (pj) (j = 1, …, k-1) and sends the same to the random substitution device (pk). Each of the random substitution devices (pj) generates an additive secure dispersion value (<>ρi+1 pj) using a random number (rj).