Paper 2012/421

Security margin evaluation of SHA-3 contest finalists through SAT-based attacks

Ekawat Homsirikamol and Pawel Morawiecki and Marcin Rogawski and Marian Srebrny

Abstract

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 applied is called logical cryptanalysis where the original task is expressed as a SATisfiability problem instance. A new toolkit is used to simplify the most arduous stages of this type of cryptanalysis and helps to mount the attacks in a uniform way. 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. Two other metrics, software performance and hardware efficiency are combined with security results to provide a more comprehensive picture of the SHA-3 finalists.