SMS4 is a 128-bit block cipher used in the WAPI standard for wireless networks in China. In this paper, we analyze the security of the SMS4 block cipher against differential cryptanalysis. Firstly, we prove three theo...SMS4 is a 128-bit block cipher used in the WAPI standard for wireless networks in China. In this paper, we analyze the security of the SMS4 block cipher against differential cryptanalysis. Firstly, we prove three theorems and one corollary that reflect relationships of 5- and 6-round SMS4. Next, by these relationships, we clarify the minimum number of active S-boxes in 6-, 7- and 12-round SMS4 respectively. Finally, based on the above results, we present a family of about 2^14 differential characteristics for 19-round SMS4, which leads to an attack on 23-round SMS4 with 2^118 chosen plaintexts and 2^126.7 encryptions.展开更多
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 ...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.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.60873259 and 60903212the Knowledge Innovation Project of the Chinese Academy of Sciences
文摘SMS4 is a 128-bit block cipher used in the WAPI standard for wireless networks in China. In this paper, we analyze the security of the SMS4 block cipher against differential cryptanalysis. Firstly, we prove three theorems and one corollary that reflect relationships of 5- and 6-round SMS4. Next, by these relationships, we clarify the minimum number of active S-boxes in 6-, 7- and 12-round SMS4 respectively. Finally, based on the above results, we present a family of about 2^14 differential characteristics for 19-round SMS4, which leads to an attack on 23-round SMS4 with 2^118 chosen plaintexts and 2^126.7 encryptions.
基金supported by the National Basic Research 973 Program of China under Grant Nos.2013CB834201 and 2013CB834205the Postdoctoral Science Foundation of China under Grant No.2013M540786the National Natural Science Foundation of China under Grant Nos.61202493 and 61103237
文摘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.
