Cryptanalysis of Some Double-Block-Length Hash Modes of Block Ciphers with n-Bit Block and n-Bit Key

In this paper, we make attacks on DBL (Double-Block-Length) hash modes of block ciphers with n-bit key and n-bit block. Our preimage attack on the hash function of MDC-4 scheme requires the time complexity 2, which is significantly improved compared to the previous results. Our collision attack on the hash function of MJH scheme has time complexity less than 2 for n = 128. Our preimage attack on the compression function of MJH scheme find a preimage with time complexity of 2. It is converted to a preimage attack on the hash function with time complexity of 2. Our preimage attack on the compression function of Mennink’s scheme find a preimage with time complexity of 2. It is converted to a preimage attack on the hash function with time complexity of 2. These attacks are helpful for understanding the security of the hash modes together with their security proofs.