序列密码采样攻击的改进方法  

Improved Method for Decimation Attacks of Stream Cipher

作　　者：祁传达[1] 陈越奋[1] 王丽娜[1] 

机构地区：[1]信阳师范学院数学与信息科学学院,信阳464000

出　　处：《计算机工程》2009年第8期155-157,共3页Computer Engineering

基　　金：河南省自然科学基金资助项目(072300410030)

摘　　要：对Eric Filiol提出的采样攻击方法(Proc. of INDOCRYPT’00,Springer-Verlag出版,2000)进行改进,利用n级LFSR序列的已知相似序列的2个不同起点的d采样序列,同时攻击2个Ld级LFSR序列,得到2Ld个关于n级LFSR初态的线性无关的线性方程,再攻击LFSR初态的其余n-2Ld个比特,从而恢复n级LFSR的初态。改进后的采样攻击方法计算复杂性由Eric Filiol采样攻击的C(Ld)+C(n-Ld)降为2C(Ld)+C(n-2Ld)。This paper improves the decimation attacks method presented by Filiol. By d-decimating the known sequence from two different initial points, it can attack the initial states of two Ld-series LFSR, obtaining 2Ld independent equations with the bits of the initial state of the n-series LFSR, then attacks the other n-2Ld bit of the n-series LFSR initial states, consequently recovers the initial states of the n-series LFSR. The computational complexity of improved decimation attack is reduced from C（Ld）＋C（n-Ld） of decimation attacks presented by Filiol to 2C（Ld）＋C（n-2Ld）, where C（m） is the computational complexity of attacking m-series LFSR by correlation attacks or fast correlation attacks.

关 键 词：序列密码 采样序列 采样攻击 

分 类 号：TP309[自动化与计算机技术—计算机系统结构]