Security Assessment of Hierocrypt and Rijndael against the Differential and Linear Cryptanalysis (Extended Abstract)

The authors analyze the security of Hierocrypt-3(128-bit) and Hierocrypt-L1(64-bit) designed on the nested SPN(NSPN) structure against the differential and linear cryptanalysis, and found that they are sufficiently secure, e.g., the maximum average differential and linear hull probabilities (MACP and MALHP) are bounded by 2−96 for 4-round of Hierocrypt-3; those probabilities are bounded by 2−48 for 4-round of Hierocrypt-L1. The authors get these results by extending the provable security theorem by Hong et al.. Furthermore, the extended theory is applied to Rijndael, and found that MACP and MALHP of 4-round Rijndael are bounded by 2−96. This outperforms the best previous result by Keliher et al..