1 Department of Applied Mathematics and Computer Science, Technical University of Denmark2 Cryptology, Department of Applied Mathematics and Computer Science, Technical University of Denmark3 Shanghai Jiao Tong University4 Katholieke Universiteit5 Shandong University
In this paper, we present more powerful 6-round impossible differentials for large-block Rijndael-224 and Rijndael-256 than the ones used by Zhang et al. in ISC 2008. Using those, we can improve the previous impossible differential cryptanalysis of both 9-round Rijndael-224 and Rijndael-256. The improvement can lead to 10-round attack on Rijndael-256 as well. With 2198.1 chosen plaintexts, an attack is demonstrated on 9-round Rijndael-224 with 2 195.2 encryptions and 2140.4 bytes memory. Increasing the data complexity to 2216 plaintexts, the time complexity can be reduced to 2130 encryptions and the memory requirements to 2 93.6 bytes. For 9-round Rijndael-256, we provide an attack requiring 2229.3 chosen plaintexts, 2194 encryptions, and 2 139.6 bytes memory. Alternatively, with 2245.3 plaintexts, an attack with a reduced time of 2127.1 encryptions and a memory complexity of 290.9 bytes can be mounted. With 2244.2 chosen plaintexts, we can attack 10-round Rijndael-256 with 2253.9 encryptions and 2186.8 bytes of memory.
Lecture Notes in Computer Science: 15th International Conference, Seoul, Korea, November 28-30, 2012, Revised Selected Papers, 2013, p. 126-140
Block cipher; Impossible differential attack; Rijndael; Large block
Main Research Area:
Lecture Notes in Computer Science
15th Annual International Conference on Information Security and Cryptology (ICISC 2012)Information Security and Cryptology