Algebraic Precomputations in Differential Cryptanalysis

International audienceAlgebraic cryptanalysis is a general tool which permits one to assess the security of a wide range of cryptographic schemes. Algebraic techniques have been successfully applied against a number of multivariate schemes and stream ciphers. Yet, their feasibility against block ciphers remains the source of much speculation. In this context, algebraic techniques have mainly been deployed in order to solve a system of equations arising from the cipher, so far with limited success. In this work we propose a different approach: to use Gröbner basis techniques to compute structural features of block ciphers, which may then be used to improve “classical” differential and integral attacks. We illustrate our techniques against the block ciphers Present and Ktantan 32