SECURE AGGREGATE SUM SYSTEM, SECURE COMPUTATION DEVICE, SECURE AGGREGATE SUM METHOD, AND PROGRAM

摘要

The present invention efficiently finds an aggregate sum while maintaining confidentiality. According to the present invention, a prefix sum unit (11) computes prefix sums from shares for sorted value attributes. A flag conversion unit (12) performs a format conversion on shares for flags that represent the final elements of groups. A flag application unit (13) generates a share for a vector in which a prefix sum is set when the flag that represents the final element of a group is true and in which a sum is set when the flag is false. A sort unit (14) generates a share for a sorted vector that is the result of the vector being sorted by permutation that arranges the final elements of the groups in order from the top. A sum computation unit (15) generates a share for a vector in which the differences between the values of given elements of the sorted vector and the values of the previous elements are set and that represents the sum of each group.