Related Key Differential Attacks on 27 Rounds of XTEA and Full-Round GOST

摘要

In this paper, we present a related key truncated differential attack on 27 rounds of XTEA which is the best known attack so far. With an expected success rate of 96.9%, we can attack 27 rounds of XTEA using 2~(20.5) chosen plaintexts and with a complexity of 2~(115.15) 27-round XTEA encryptions. We also propose several attacks on GOST. First, we present a distinguishing attack on full-round GOST, which can distinguish it from a random permutation with probability 1 - 2~84 using a related key differential characteristic. We also show that H. Seki et al.'s idea combined with our related key differential characteristic can be applied to attack 31 rounds of GOST. Lastly, we propose a related key differential attack on full-round GOST. In this attack, we can recover 12 bits of the master key with 2~(35) chosen plaintexts, 2~(36) encryption operations and an expected success rate of 91.7%.