Distinguishing attacks on generalized self-shrinking generators
Fengrong Zhang · Journal of Xidian University · 2012
With simple construction and easy implementation,the generalized self-shrinking generator is a keystream generator intended to be used as a stream cipher.This paper investigates the security of the generalized self-shrinking generator.We propose two distinguishing attacks on the generalized self-shrinking sequences by using the feedback polynomial and the sequence v.The results show that the attacker can launch a distinguishing attack by choosing the hw-1 keystream bit of the generalized self-shrinking generator,if the feedback polynomial f(x) is of hamming weight w and degree h.On the other hand,if the hamming weight of f(x) is low,then the attacker can launch a distinguishing attack,and the attack complexity depends on the weight of f(x).Therefore,neither type of the polynomials can be chosen as the feedback polynomials of the generalized self-shrinking generator.Users should choose the feedback polynomial carefully,otherwise the stream cipher can suffer from distinguishing attacks.