A Comparison of Local Reduction and Sat-Solver Based Algebraic Cryptanalysis of Jh And Keccak

Local reduction methods can be used to assess the resistance of cryptosystems against algebraic attacks. The assessment is based on the separation of the attack into polynomial-time reduction algorithm, and exponential time guessing and backtracking. This approach is similar to that employed by the DPLL algorithm that is used as a core of various modern SAT-solvers. In the article we show the application of this method to evaluate the strength of (reduced versions of) two chosen SHA-3 candidates: JH, and Keccak, respectively. We compare the complexity estimates with the behavior of the full search algorithm. We also compare the results based on the local reduction with the attack based on the use of SAT-solvers PrecoSAT, and CryptoMiniSAT, respectively.