混沌理论分析及在保密通信中的应用研究

【作者】 张政伟；

【导师】 李宏；

【作者基本信息】 西北工业大学 ， 电路与系统， 2005， 硕士

【摘要】 混沌以其拥有的诸多天然优良特性而倍受关注,并在很多领域得到了广泛和成功的应用。通过对混沌系统的分析研究,可以更好地把握混沌的特性,为应用混沌打下坚实的理论基础;控制混沌是混沌走向应用的前提,研究混沌的控制,可以为应用混沌提供更多的技术支撑。本文以混沌在保密通信中的应用为研究背景,对计算混沌系统特征参数的方法和控制混沌的方法作了深入的分析研究。本文的主要内容如下: 1.研究了混沌系统各种特征参数的典型计算方法。鉴于由小数据量方法计算的最大Lyapunov指数具有随潜入维数的变化有明显波动的缺点,本文提出了用C-C方法同时回归出潜入维数m和时间延迟τ的改进方法,计算机仿真结果表明了该改进方法的正确性和有效性。 2.给出了在一般信号驱动下混沌控制的三种典型方法,即自适应控制方法、采样数据反馈控制方法和滑模变结构控制方法。针对现有自适应控制方法中存在的控制器不连续的缺陷,提出了在分母上增加指数项的改进方案,计算机仿真结果表明了该改进方法的有效性。 3.对在混沌信号驱动下的混沌控制即混沌同步问题,给出了基于状态观测器的混沌同步控制和基于锁相环的混沌同步控制方法,并对基于锁相环的混沌同步算法的鲁棒性进行了深入分析和理论研究,作出了新的理论结论。 4.研究了混沌在现代密码学中的应用,通过实例验证了混沌信号作为密钥的可行性和高可靠性。介绍了基于锁相环和混沌不稳定周期轨道的两种混沌保密通信方法。理论上论证了混沌信号用于保密通信的可行性。更多还原

【Abstract】 Chaos has been paid wide attention because of its some good intrinsic properties, such as wide-band frequency, similarity to noise and extremely sensitivity to initial condition, and it has been widely and successfully applied to many areas. Analyzing chaotic system and researching chaos control, which is the premise for the application of the chaos, can make us know more special properties of the chaos. Some methods of computing the characteristic parameters of the chaotic system and some methods of controlling the chaos for the secured communication are presented in detail. The main contributions of this dissertation are as follows:1. All kinds of typical methods of computing the characteristic parameters of the chaos are presented at length. Aiming at the default of the Small-Set methods whose results are varied obviously with the variation of the embedding dimension, we computer jointly the embedding dimension and time delay by using the famous C-C methods. The simulation results show that the improving measures are correct and efficient.2. Three typical methods of controlling chaos when the chaotic systems are driven by a common signal are discussed at length firstly, namely adaptive method, sampled data feedback method and moving surface method. We presented the improving measures of the adaptive method and the moving surface method respectively.3. Methods based on the observer and based on the phase-locked loops are discussed comprehensively in this dissertation when the chaotic systems are driven by a chaotic signal. Especially we researched the robustness of the method based on the phase-locked loops deeply, and new theory on computation robustness presented.4. The typical and successful applications in the modern cryptology of the chaos are discussed in this dissertation, and the simulation results substantiate the feasibility and the high reliability of the chaotic key with a concrete instance. Two secured communication designs, one based on phase-locked loops and another based on the unstable periodic trajectory of the chaos, are discussed comprehensively. The simulation results show that applying the chaos in the secured communication is very effective in theory.更多还原