Improved Meet-in-the-Middle Attacks on AES

This paper studies key-recovery attacks on AES-192 and PRINCE under single-key model by methodology of meet-in-the-middle attack. A new technique named key-dependent sieve is proposed to further reduce the memory complexity of Demirci et al.’s attack at EUROCRYPT 2013, which helps us to achieve 9-round attack on AES-192 by using a 5-round distinguisher; the data, time and memory complexities are 2 chosen plaintexts, 2 encryptions and 2 128bit memories, respectively. The new technique is also applied to attack block cipher PRINCE. Instead of 6-round results in the previous cryptanalysis, we first present attacks on 8-round (out of 12) PRINCEcore and PRINCE with about 2 and 2 encryptions, respectively. Furthermore, we construct an interesting 7-round distinguisher and extend the attack to 9-round PRINCE; the attack needs about 2 chosen plaintexts, 2 encryptions and 2 64-bit memories.