SMBA分组密码的不可能差分分析OA

The SMBA block cipher is an award-winning algorithm of the recent Cryptographic Algorithm Design Competition in China.It includes three versions SMBA128-128,SMBA128-256,and SMBA256.For impossible differential cryptanalysis of SMBA,Li et al.proposed 6-round impossible differentials of SMBA128 in 2023 with one more round than the designers'and new 8-round impossible differentials of SMBA256,and launched attacks on 9-round SMBA128-128 and 12-round SMBA256.By utilizing some more specific relations among the differences at both plaintexts and ciphertexts as well as the expected intermediate differences and techniques for efficiently screening plaintext-ciphertext pairs,this study improves Li et al.'s impossible differential attacks on 9-round SMBA128-128 and 12-round SMBA256,gives new 6-round impossible differentials of SMBA128,and presents impossible differential attacks on 11-round SMBA128-256 based on the Li et al.'s and the proposed 6-round impossible differentials of SMBA128.These are better than any previously published impossible differential cryptanalytic results on SMBA.