A SAT-based preimage analysis of reduced Keccak hash functions

• We have carried out the SAT-based preimage attack on reduced Keccak hash function.
• We have found a preimage and partial preimages for reduced versions of Keccak hash function.
• The results suggest the strength of the Keccak function against the SAT-based attack.

In this paper, we present a preimage attack on reduced versions of Keccak hash functions. We use our recently developed toolkit CryptLogVer for generating the conjunctive normal form, CNF, which is passed to the SAT solver PrecoSAT. We found preimages for some reduced versions of the function and showed that full Keccak function has a comfortable security margin against this kind of attack.