Automatic Search of Truncated Impossible Dierentials for Word-Oriented Block Ciphers (Full Version) ?
Shengbao Wu, Ming‐Sheng Wang · 2012
Impossible dierential cryptanalysis is a powerful technique to recover the secret key of block ciphers by exploiting the fact that in block ciphers specic input and output dierences are not compatible. This paper introduces a novel tool to search truncated impossible dierentials for word-oriented block ciphers with bijective Sboxes. Our tool generalizes the earlierU-method and the UID-method. It allows to reduce the gap between the best impossible dierentials found by these methods and the best known dierentials found by ad hoc methods that rely on cryptanalytic insights. The time and space complexities of our tool in judging an r-round truncated impossible dierential are about