Improved Linear Attacks on the Chinese Block Cipher Standard  

作　　者：刘明洁 陈佳哲 

机构地区：[1]Beijing International Center for Mathematical Research,Peking University [2]China Information Technology Security Evaluation Center

出　　处：《Journal of Computer Science & Technology》2014年第6期1123-1133,共11页计算机科学技术学报（英文版）

基　　金：supported by the National Basic Research 973 Program of China under Grant Nos.2013CB834201 and 2013CB834205;the Postdoctoral Science Foundation of China under Grant No.2013M540786;the National Natural Science Foundation of China under Grant Nos.61202493 and 61103237

摘　　要：The block cipher used in the Chinese Wireless LAN Standard （WAPI）, SMS4, was recently renamed as SM4, and became the block cipher standard issued by the Chinese government. This paper gives a method for finding the linear approximations of SMS4. With this method, 19-round one-dimensional approximations are given, which are used to improve the previous linear cryptanalysis of SMS4. The 19-round approximations hold with bias 2-62.27; we use one of them to leverage a linear attack on 23-round SMS4. Our attack improves the previous 23-round attacks by reducing the time complexity. Furthermore, the data complexity of our attack is further improved by the multidimensional linear approach.The block cipher used in the Chinese Wireless LAN Standard （WAPI）, SMS4, was recently renamed as SM4, and became the block cipher standard issued by the Chinese government. This paper gives a method for finding the linear approximations of SMS4. With this method, 19-round one-dimensional approximations are given, which are used to improve the previous linear cryptanalysis of SMS4. The 19-round approximations hold with bias 2-62.27; we use one of them to leverage a linear attack on 23-round SMS4. Our attack improves the previous 23-round attacks by reducing the time complexity. Furthermore, the data complexity of our attack is further improved by the multidimensional linear approach.

关 键 词：block cipher SMS4 linear cryptanalysis multidimensional linear cryptanalysis 

分 类 号：TN925.93[电子电信—通信与信息系统] TN918.1[电子电信—信息与通信工程]