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计算机工程 ›› 2009, Vol. 35 ›› Issue (8): 155-157. doi: 10.3969/j.issn.1000-3428.2009.08.052

• 安全技术 • 上一篇    下一篇

序列密码采样攻击的改进方法

祁传达,陈越奋,王丽娜   

  1. (信阳师范学院数学与信息科学学院,信阳 464000)
  • 收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:2009-04-20 发布日期:2009-04-20

Improved Method for Decimation Attacks of Stream Cipher

QI Chuan-da, CHEN Yue-fen, WANG Li-na   

  1. (College of Mathematics and Information Science, Xinyang Normal University, Xinyang 464000)
  • Received:1900-01-01 Revised:1900-01-01 Online:2009-04-20 Published:2009-04-20

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)。

关键词: 序列密码, 采样序列, 采样攻击

Abstract: 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.

Key words: stream cipher, decimation sequence, decimation attacks

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