A Meet-in-the-Middle Attack on ARIA

In this paper, we study the meet-in-the-middle attack against block cipher ARIA. We find some new 3-round and 4-round distinguishing properties of ARIA. Based on the 3-round distinguishing property, we can apply the meet-in-the-middle attack with up to 6 rounds for all versions of ARIA. Based on the 4-round distinguishing property, we can mount a successful attack on 8-round ARIA-256. Furthermore, the 4-round distinguishing property could be improved which leads to a 7round attack on ARIA-192. The data and time complexities of 7-round attack are 2 and 2, respectively. The data and time complexities of 8-round attack are 2 and 2, respectively. Compared with the existing cryptanalytic results on ARIA, our 5-round attack has the lowest data and time complexities and the 6-round attack has the lowest data complexity. Moreover, it is shown that 8-round ARIA-256 is not immune to the meet-in-the-middle attack.