Security Evaluation of Double-Block-Length Hash Modes with Preimage Attacks on PGV Schemes

Abstract

In FSE 2011, Sasaki presented the preimage attacks on Davies-Meyer (DM) scheme of 7-round AES and explained conversion of it to the attack on the hash function for 12 secure PGV schemes. In this paper, we apply Sasaki's work to Double-Block-Length (DBL) hash modes based on arbitrary blockcipher. We generalize compression functions in several DBL hash modes. Assuming a Sasaki's preimage attack on DM scheme of the underlying blockcipher is faster than brute-force attack, we evaluate securities of the hash modes against preimage or second-preimage attacks. Hence, we analyzed the hash modes against preimage or second-preimage attacks except some case of the generalized MDC-4.