Hash value calculation device, hash value calculation method, and non-transitory computer-readable storage medium including computer executable instruction

Abstract

The object is to constitute a hash function by removing a feed-forward arithmetic operation. A hash value calculation device, for each integer i of i=1, . . . , L in an ascending order, calculates a function f[i] which, upon input of a value M[i] having k-n bits, an n-bit value y−1] (a value y] is a predetermined value IV), and an n-bit value y−1] (a value y] is a predetermined value IV), outputs an n-bit value x], an n-bit value x], a k-bit value k], and a k-bit value k]; for the value x] as a plaintext and the value k] as a key, calculates an n-bit value y] with an encryption function of a block cipher; and for the value xas a plaintext and the value k] as a key, calculates an n-bit value y] with the encryption function for the block cipher. The hash value calculation device, upon input of a value y[L] and a value y[L] which are calculated, calculates a hash value with an injective function g.