Secret sigmoid function calculation system, secret logistic regression calculation system, secret sigmoid function calculation device, secret logistic regression calculation device, secret sigmoid function calculation method, secret logistic regression calculation method, program

摘要

A technique for performing secure computation of a sigmoid function with high speed and precision is provided. A secret sigmoid function calculation system is a system, in which g(x) is assumed to be a secure computable function, which calculates, from a share [[x]] of an input value x, a share [[σ'(x)]] of a value of a sigmoid function for the input value x, and includes: a first comparing means that generates a first comparison result [[c]] = less_than([[x]], t1); a second comparing means that generates a second comparison result [[d]] = greater_than([[x]], t0); a first logical computation means that generates a first logical computation result [[e]] = not([[c]]); a second logical computation means that generates a second logical computation result [[k]] = and([[c]], [[d]]) or [[k]] = mul([[c]], [[d]]); and a function value calculating means that calculates the share [[σ'(x)]] = mul([[k]], [[g(x)]])+[[e]].