SERVER DEVICE, SECRET EQUALITY DETERMINATION SYSTEM, SECRET EQUALITY DETERMINATION METHOD AND SECRET EQUALITY DETERMINATION PROGRAM STORAGE MEDIUM

摘要

A server device, a secret equality determination system, a secret equality determination method and a secret equality determination program storage medium are provided which, regardless of the secret sharing scheme, can run with no difference in the number of communication rounds, whether carried out with a ring of order 2 or with a ring of an order greater than 2. This server device is provided with a secret sharing data generation unit, a data storage unit, a mask unit, a random number share bit-conjunction unit, a random number share generation unit, a determination bit-conjunction unit and a secret sharing data restoration unit. The secret sharing data generation unit generates secret sharing data. The data storage unit stores the secret sharing data. The mask unit uses random number secret sharing data to mask certain secret sharing data. The random number share generation unit generates random number shares in which random numbers are secretly shared. In parallel with other calculations, the random number share bit-conjunction unit calculates the logical product of the values in which the random numbers are secretly shared. The determination bit-conjunction unit performs a secret equality determination using the value outputted by the random number share bit-conjunction unit.