Analysis of (k0,k1) Clock-Controlled Sequences

摘要

Cryptographic sequence generators are discussed in which a linear feedback shift register (LFSR) is clock controlled in a pseudorandom manner by another register. A model of clock-controlled sequences is proposed. The necessary and sufficient condition guaranteeing the maximal linear complexity and the maximal period of such sequences is given. Two kinds of improved models having better statistical properties are given. In order to study the security of this model, three types of algebraic attacking algorithms are proposed. If the length of the second LFSR in such a model is large, the model can resist our algebraic attacks.