Impossible Differential Cryptanalysis of 7-Round ARIR-192

ARIA cipher is a new block cipher proposed by some South Korean experts in 2003. The design principle of ARIA is similar to the AES. ARIA is established as a Korean Standard block cipher algorithm by Korean Agency for Technology and Standards. In this paper, a new impossible differential attack on 7 rounds of the ARIA cipher is presented. By this attack, 7-round ARIA-192 is breakable with a data complexity of about2176.2 encryptions,while the previous best impossible differential attack on ARIA broke on 7-round ARIA-256. Then some characters on diffusion layer are used to reduce the complexity of the ARIA-256 to 2192.2.