Secret bulk approximation system, secret calculation device, secret bulk approximation method and program

摘要

Calculation time is reduced without degrading approximation accuracy in calculation of a complicated function through secure computation. A secret batch approximation system (100) calculates a concealed text [z] of an approximate value z for a function value y satisfying yj = f(xj) by using a concealed text [x] of a value x as input. g is defined as a polynomial for approximating each section of m sections into which the function f is divided. A parameter acquisition unit (12) acquires a concealed text [a] of a parameter a corresponding to the value x for each integer j that is not less than 1 and not more than n, where aj is defined as a parameter pi corresponding to a section Ri including a value xj. A polynomial calculation unit (13) calculates a polynomial g([x], [a]) by using the concealed text [x] of the value x as input based on the concealed text [a] of the parameter a so as to obtain the concealed text [z] of the approximate value z for the function value y.