Improved Method for Decimation Attacks of Stream Cipher
Lina Wang · Jisuanji gongcheng · 2009
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.