关键词: 分组密码, 不可能差分分析, ARIA, 数据复杂性, 时间复杂性

Abstract:

The security of the block cipher ARIA against impossible differential cryptanalysis is studied. First, we analyze the diffusion layer of ARIA and indicate some differential characters of the intermediate state through the encryption transformation. On the basis of these, we show that there is no 6-round impossible differential with the input-and-output differential weight less than ten and that there are only two kinds of 6-round impossible differential with the input-and-output differential weight of ten. Both kinds of the best impossible differentials can be found and can be used to attack the 6-round ARIA with the best results: the data complexity being 2¹²⁰ chosen plaintexts and the time complexity being 2^94.5 encryptions of 6-round ARIA.

Key words: block cipher, impossible differential cryptanalysis, ARIA, data complexity, time complexity