Cryptanalysis of the reduced-round version of JH

The JH hash function, introduced by Wu, is the one of the algorithms that was selected to the final round of SHA3 competition. In this paper, we are proud to present two kinds of attack on JH-512 hash function. One of them is a pre-image attack on the 10 rounds and the other is a collision attack on the 6 rounds of the compression function of JH. The former complexity is 2³²⁵ and the later one has a complexity of 2³³⁷. First of all, we consider JH hash function with the d=4 and explain the pre-image attack on it. And finally we give proper differential trails for the 512-bit version (d=8) of JH. Despite of the good result of this paper for breaking this hash function, the system has not broken till now.