摘要：The strict avalanche criterion(SAC)is one of the most important cryptographic criteria for substitution boxes(S-boxes)used in many symmetric encryption ***,there are few constructive methods for S-boxes fulfilling the SAC until *** this paper,to construct S-boxes satisfying the SAC directly,we generalize the concatenation techniques of Boolean functions to *** the idea of concatenating small variable S-boxes,we present a simple yet effective construction method of S-boxes satisfying the ***,a simple example on how to construct SAC S-boxes with large input variables by small variables SAC S-boxes is given.