FBC (Feistel-based Block Cipher) is a lightweight block cipher selected in the second round of the Nation-al Cryptographic Algorithm Design Competition. It has many advantages such as simple algorithm structure,high security and excellent implementation performance,and has attracted much attention in the industry. The block size and key length of FBC are at least 128 bits,denoted as FBC-128. At present,the best result of differential attack on FBC-128 is 12-round. The time complexity is 293.41 encryptions,and the data complexity is 2122 chosen-plaintexts. However,it is still to be solved whether there is a longer differential distinguisher and higher rounds of key recovery attack on FBC. In this paper,a segmen-tal statistical method is proposed to search the differential characteristic of FBC-128 based on the mixed-integer linear pro-gramming technology. The results show that FBC-128 exists15-round differential distinguisher with probability 2-121. Then,we extend it backward by one round,and launch a key recovery attack on 16-round FBC-128.The data complexity is 2121 chosen-plaintexts,and the time complexity is 292.68 encryptions. Compared with the existing results,the differential distin-guisher and key recovery attacks are increased by 4 rounds with lower data and time complexity.
关键词
自动化分析/混合整数线性规划/分组密码算法/差分区分器/密钥恢复攻击/FBC算法
Key words
automatic analysis/mixed-integer linear programming/block cipher/differential distinguisher/key recovery attack/FBC cipher
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