LEX算法的相关密钥攻击

LEX算法是入选欧洲序列密码工程eSTREAM第三阶段的候选流密码算法之一,在分组密码算法AES的基础上进行设计。为此,针对LEX算法进行基于猜测决定方法的相关密钥攻击,在已知一对相关密钥各产生239.5个字节密钥流序列的条件下,借助差分分析的思想和分组密码算法AES轮变换的性质,通过穷举2个字节密钥值和中间状态的8个字节差分恢复出所有候选密钥,利用加密检验筛选出正确的密钥。分析结果表明,该密钥攻击的计算复杂度为2100.3轮AES加密、成功率为1。

Related-key Attack on LEX Algorithm

LEX is one of stream cipher algorithms that progressed to Phase 3 of the eSTREAM project, and it is designed based on block cipher algorithm AES. In this paper, a related-key attack based on guess and determination attack for LEX cipher is proposed. If 2 39.5 Byte key streams under a pair of related-keys respectively are known, with the method of differential cryptanalysis and some properties of AES, the attack can recover the entire candidate keys by guessing 2 Byte key and 8 Byte difference of the internal state, and then find the correct key by encipher test. Analysis results show that the success ratio is 1, and the time complexity is 2 100.3 AES encipher operations.