Fast algorithm to search for the minimum number of active S-boxes of block cipher.

To solve the problem of fast calculation of the minimum number of active S-boxes in cryptographic design, the difference and mask propagation of the diffusion layer were investigated, and a method was proposed to compute the difference (resp. mask) pattern distribution table of MDS (maximum distance separable) matrices and binary matrices. A lower bound on the computation complexity of the proposed method was also given. Based on the difference (resp. mask) pattern distribution table of diffusion matrix, a fast algorithm to search for the minimum number of active S-boxes of block cipher was proposed. The proposed algorithm is applied to some SPN (substitution permutation network) block ciphers, and finds the minimum number of active S-boxes for the full round of LED, SKINNY, CRAFT and FIDES. [ABSTRACT FROM AUTHOR]