Hash value computation device, hash value computation method, and computer readable medium

Abstract

A hash value computation device (10) computes a hash value H of 2n bits using a block cipher E that takes as input a key K of k bits and a plaintext block P of n bits, which is a smaller number of bits than k bits, and outputs a ciphertext of n bits. A function computation unit (22) computes a function CF that processes the block cipher E a plurality of times sequentially on an input value M* of k−n bits, an input value S[1] of n bits, and an input value S[2] of n bits so as to compute an output value S′[1] of n bits and an output value S′[2] of n bits. A hash value computation unit (23) computes the hash value H from the output value S′[1] and the output value S′[2].

CPC Classifications