Improved Security for Chaos-based Stream Cryptosystems by Multi-layer Synchronization Systems

摘要

Application of deterministic chaos in secure communication brings advantages over conventional methods in the sense that messages are combined with chaotic signals for transmission. In chaos-based secure communication systems, the parameters and initial condition of chaotic systems are regarded as a secrete key and are known in the transmitter and receiver sides. The range of parameters, however, is restricted by chaotic behavior of dynamical systems. In this report, a new model of chaos-based stream cryptosystem for secure communication is proposed in terms of multi-layer synchronization system such that the range of parameters can be expanded as in the case of the parameters of chaotic systems. Moreover, the chaotic systems, which produce the chaotic signals for the keystream generators, are hidden by the multi-layer synchronization. Besides that a new scheme of the keystream generation is given in which instant keys are much more sensitive to the evolution of chaotic variables beyond the conventional ones. The numerical simulation is accomplished to demonstrate the effectiveness of the presently proposed system.