针对流密码K2算法的猜测决定攻击

Guess and Decision Attack for Stream Cipher K2 Algorithm

针对K2算法进行猜测决定攻击,指出猜测9个状态的攻击结果不正确,并给出一组猜测10个状态的攻击结果。修正无LFSR-A的简化K2算法的猜测决定攻击结果,使计算复杂度由O(2192)降低至O(2160)。分析结果表明,在K2算法中,利用LFSR-A引入动态反馈多项式控制机制可以提高算法的抵抗猜测决定攻击能力。

This paper proves that the resulting guess and determine attack on K2 which needs only 9 guessed elements is incorrect,introduces a guess-and-determine attack with the result of 10 guessed elements,and reduces the computational complexities from O（2192） to O（2160） by implementing guess and determine attack on the simplified K2 without LFSR-A.Analysis results show that the dynamic feedback control mechanism introduced by K2 has strong resistance against guess and determine attacks.