Improved Results of Impossible Differential Cryptanalysis on Reduced FOX
Xinran Li, Chenhui Jin, Fang‐Wei Fu · The Computer Journal · 2015
FOX is a family of block ciphers published in 2004 and several attacks on reduced FOX have been published, and the best known attacks are on 7-round FOX64 and 5-round FOX128. In this paper, we present impossible differential attacks on 8-round FOX64 and 6-round FOX128 with various techniques such as the multiple differentials, the state-test technique, the quick sort method and the early abort technique. For 8-round FOX64, the data complexity and the time complexity is |$2^{42}$| and |$2^{239.54}$| one-round encryptions, respectively, and the memory required is |$2^{44}$| bytes. For 6-round FOX128, the data complexity and the time complexity is |$2^{75}$| and |$2^{209.55}$| one-round encryptions, respectively, and the memory required is |$2^{77}$| bytes.