Security Margin Evaluation of SHA-3 Contest Finalists through SAT-Based Attacks

In 2007, the U.S. National Institute of Standards and Technology (NIST) announced a public contest aiming at the selection of a new standard for a cryptographic hash function. In this paper, the security margin of five SHA-3 finalists is evaluated with an assumption that attacks launched on finalists should be practically verified. A method of attacks is called logical cryptanalysis where the original task is expressed as a SATisfiability problem. To simplify the most arduous stages of this type of cryptanalysis and helps to mount the attacks in a uniform way a new toolkit is used. In the context of SAT-based attacks, it has been shown that all the finalists have substantially bigger security margin than the current standards SHA-256 and SHA-1.