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Security and Communication Networks
Volume 2017, Article ID 5980251, 9 pages
Research Article

Improvements for Finding Impossible Differentials of Block Cipher Structures

1School of Electronics and Information, Shanghai Dian Ji University, Shanghai, China
2Department of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
3Westone Cryptologic Research Center, Beijing 100070, China

Correspondence should be addressed to Yiyuan Luo; nc.ude.ujds@yyoul

Received 30 March 2017; Accepted 17 July 2017; Published 29 August 2017

Academic Editor: Jesús Díaz-Verdejo

Copyright © 2017 Yiyuan Luo and Xuejia Lai. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We improve Wu and Wang’s method for finding impossible differentials of block cipher structures. This improvement is more general than Wu and Wang’s method where it can find more impossible differentials with less time. We apply it on Gen-CAST256, Misty, Gen-Skipjack, Four-Cell, Gen-MARS, SMS4, MIBS, , LBlock, E2, and SNAKE block ciphers. All impossible differentials discovered by the algorithm are the same as Wu’s method. Besides, for the 8-round MIBS block cipher, we find 4 new impossible differentials, which are not listed in Wu and Wang’s results. The experiment results show that the improved algorithm can not only find more impossible differentials, but also largely reduce the search time.