Searching for impossible subspace trails and improved impossible differential characteristics for SIMON-like block ciphers

Abstract In this paper, we greatly increase the number of impossible differentials for SIMON and SIMECK by eliminating 1-bit constraint in input/output difference, which is precondition to ameliorate complexity attacks. We propose an algorithm can reduce searching find such trails efficiently since search space exponentially expands with multiple active bits. There another situation leading contradiction except miss-in-the-middle. show how happens conclude it defined as miss-from-the-middle. It makes our results more comprehensive applying these two approach simultaneously. This paper gives first time differential characteristics bits SIMECK, a great number. The be verified not only covering state-of-art, but also MILP model.