A
secret sharing apparatus according to the present invention is based on a (k,n)-threshold scheme with a threshold of at least 4. The
secret sharing apparatus generates a
generator matrix (G) of GF(2) in which any k of n column vectors are at a full rank, divides secret information into n−1 pieces to generate divided secret data (K(1), . . . , K(n−1)), generates random data (U(0,1), . . . , U(k−2,n−1)), calculates the product of matrixes of the divided secret data, the random data, and the
generator matrix (G), assigns the j×(n−1)+ith column of the calculation result to sharing partial data (D(j,i)) to calculate sharing partial data (D(j,1)), generates header information (H(j)), and individually distributes n pieces of sharing information (D(0), . . . , D(n−1)) made up of the header information (H(j)) and sharing partial data (D(j,i)) to n storage apparatuses.