Related-key rectangle cryptanalysis of Rijndael-160 and Rijndael-192

In this study, the authors present the first related-key rectangle cryptanalysis of Rijndael-160/160 and Rijndael-192/192. The author´s attack on Rijndael-160/160 covers eight rounds. The attack complexities are 2^126.5 chosen plaintexts, 2^129.28 8-round Rijndael-160/160 encryptions and 2^132.82 bytes. Their attack on Rijndael-192/192 covers ten rounds. It requires 2¹⁷⁹ chosen plaintexts, 2^181.09 10-round Rijndael-192/192 encryptions and 2^185.59 bytes memory. These are the currently best cryptanalytic results on Rijndael-160/160 and Rijndael-192/192 in terms of the number of attacked rounds. Furthermore, their results show that the slow diffusion in the key schedule of Rijndael makes it a target for this type of analysis.