SECURE EQUIJOIN SYSTEM, SECURE EQUIJOIN DEVICE, SECURE EQUIJOIN METHOD, AND PROGRAM

A secure equijoin technique of generating one table from two tables while curbing the volume of communications traffic is provided. The technique includes: a first permutation generating means 110 that generates a permutation from an element sequence which is generated from the first column of a table L and the first column of a table R; a first column generating means 120 that generates, for j = 2, .., a, by using the permutation , a prefix sum, and an inverse permutation , the j-th column of a table J from an element sequence which is generated from the j-th column of the table L; a join-result element sequence generating means 130 that generates a join-result element sequence from an element sequence ([[1]], .., [[1]], [[0]], .., [[0]], [[-1]], .., [[-1]]) by using the permutation , the prefix sum, and the inverse permutation ; a second column generating means 140 that generates, for j = a+1, .., a+b-1, the j-th column of the table J by using the join-result element sequence and the j-a+1-th column of the table R; and a third column generating means 150 that generates the first column of the table J by using the join-result element sequence and the first column of the table R.