一种破译混沌直接序列扩频保密通信的方法

提出了一种新型的混沌保密通信破译方法，并破译了混沌直接序列扩频保密通信(简称混沌直扩).针对混沌直扩信号中只有一个混沌吸引子的特点，基于混沌系统广义同步的思想，提出了混沌拟合方法；针对混沌直扩中混沌实值序列和数字信号相乘的特点，充分利用混沌直扩的基本原理和信息码是慢变信号的特性，提出了用无先导卡尔曼滤波混沌拟合的方法估计信息码的破译方法；进一步针对无先导卡尔曼滤波的过程噪声和混沌拟合的拟合误差共同导致的跟踪误差，提出了跟踪误差控制因子的方法，从而将跟踪误差转变成有利因素并加以利用，根据跟踪误差的值域范围破

Breaking a chaotic direct sequence spreading spectrum secure communication system

In this paper, a novel method is proposed for the breaking of chaotic direct sequence spread spectrum (CD3S) secure communication system. Chaotic fitting is defined based on the concept of generalized synchronization, then the method based on unscented Kalman filter and chaotic fitting is presented based on the principle of CD3S and the characteristic that the information symbol varies slowly. Furthermore, addressing to the tracking error induced by the processing noise and chaotic fitting error, a modified unscented Kalman filter based on tracking-error-controlled factor is suggested. The CD3S is unmasked according to the error-amplitude of the tracking-error. We can extract the binary message signal from the CD3S signal without knowing either the structure or the parameters of the chaotic transmitter. Simulation results verify the method.