基于限幅特性非线性三阶自治电路的混沌遮掩保密通信

设计了一种限幅特性非线性三阶自治混沌保密通信电路系统.该系统利用串联同步三阶自治混沌电路进行信号混沌遮掩保密通信.有用信号隐藏在混沌参数中,混沌复合信号作为传送信号,在发送端和接收端之间传送.利用接收端响应系统与发送端驱动系统达到同步,可无失真地将有用信息信号检出.该方法设计简单,易于实现,并且同步速度快,实现了高质量的信息保密传送,具有很好的可行性.     

基于Wien桥的混沌保密通信系统设计

在典型的Wien桥振荡电路的基础上设计了一种混沌电路,该电路只有两个集成运放,电路简单,稳定性好。以此电路设计的保密通信系统实现了发送端与接收端之间的混沌系统的同步,最后在接收端解调出调制信号,该系统有恢复精度高、保密度高、破译难度大、执行速度快的特点,使保密通信的安全性得到提高。     

一种新的混沌同步及保密通信方式

本文提出一种新的混沌同步及保密通信方式。在发送端，将信息信号与混沌载波的和经取模运算后再嵌入混沌动力系统的迭代之中以实现调制；在接收端，用一个相应的非动力学系统从接收信号中提取混沌载波并进而恢复信息信号。研究表明，该混沌同步方式具有较强的抗干扰能力并且实现容易；该保密通信系统保密性能良好。     

基于实际信道的超混沌保密通信方案

针对宽频混沌调制信号在实际信道中传输时易失真的问题,提出一种基于实际信道的超混沌保密通信方案.该方案在接收端对混沌信号进行滤波并分解为两种信号:滤波信号和滤波后的补信号,滤波信号用来遮掩信息信号,滤波后的互补信号和调制信号求和后送入混沌发生器,保证混沌发生器不受滤波器的影响;接收端和发送端采用同样的结构,保证两个混沌发...     

一种语音混沌保密通信方案的研究与硬件实现

在硬件实验研究的基础上，建立一种环形蔡氏电路，提出用环蔡氏电路实现语音混沌保密通信的一种闭环逆系统方案，其特点是利用环形蔡氏电路的单向耦合原理，通过反馈的方法形成一个包括有用信号在内的极联闭合环路，从而实现改善端与接收端之间混沌系统的严格同步而不受有用信息调制的影响。理论分析与硬件实验结果证明，该方案同现有的其它混沌通信方案相比较，具有非线性失真小、保真度高的优点，完全能够满足传送语音信号的要求。     

基于Riccati方程的混沌同步方法及在保密通信中的应用

提出了一种基于状态观测器的混沌同步方法和混沌保南通信系统。通过解Riccati方程求得状态观测器的目标矩阵使两个混沌系统同步，用混沌调制和混沌掩盖相结合的方法将该同步方法用于保密通信，用混沌系统的多个状态量对信息信号进行复杂的加密后注入混沌系统并和混沌系统的输出信号一起传送到接收端，发送和接收系统同步后，在接收端解密恢复信息信号。通过对Chua电路和四维Rossler系统的仿真研究，所得结果证明了该方法的有效性。     

基于广义观测器实现混沌系统的同步及信息传输

将保密通信问题看成是信息信号同步问题,从全新的角度提出了一种基于广义观测器的保密通信系统.首先在不改变混沌发送系统的混沌特性的前提下,将信息信号注入到混沌发送系统中,并将其看作系统的状态量;然后在接收端设计广义观测器;最后根据发送端传来的隐藏有信息信号的混沌输出信号同步出混沌系统的状态和信息信号.此方法不需要单独设计加密解密算法,而是将收发端混沌系统的同步与信息传输用同步方法一次实现.对系统的仿真证明了该方法的有效性.     

基于Lorenz系统切换混沌同步的保密通讯

该文提出利用Lorenz系统切换混沌同步实施保密通讯的方法。构建了有一定关联的两个Lorenz混沌系统,并通过选择器在系统间随机切换;用同一种控制方法既能实现不同Lorenz系统的混沌同步,又能实现相同Lorenz系统的混沌同步;发送系统可以在Lorenz混沌系统间随机转换,传输信道中混沌调制信号也随之不断变化;接收系统将混沌调制信号解调后,即可获取有用信号。由于发送系统的可选择性,导致保密信号的多样性和随机性,因此该保密通讯方法具有更好的保密性能。     

一种基于多涡卷混沌系统的切换调制保密通信

考虑到现有切换调制保密通信的不足,设计了一种含有符号函数的同步控制器,并提出一种基于多涡卷混沌系统的切换调制保密通信方案。该方案解决了切换调制保密通信中驱动系统和响应系统过多的问题,同时也能解决驱动系统切换瞬间接收端的恢复信号与发送端的信息信号不一致的问题。理论分析与数值仿真结果的一致性表明了该切换调制保密通信方案的有效性。     

混沌反馈调制语音保密通信系统

在硬件实验研究的基础上,建立一种环形蔡氏电路,简述其工作原理及其特点。在此基础上提出用环形蔡氏电路实现混沌反馈调制的一种语音保密通信方案,分析了该方案的同步原理,讨论了发送端和接收端电路参数匹配情况下的同步收敛特性,设计了硬件实验电路,进行了语音混沌保密通信的硬件实验研究,给出了实验结果。     

混沌电路同步及其在通信中的应用研究

混沌在实际系统中是很常见的，但直到最近工程人员大都把它作一种无用的东西并极力去避免它。本文给出了一个蔡氏电路系统在固有的混沌模式下实现同步的可能性。     

Chaos synchronisation of the third-order Phase-locked Loop

In this article, the desirable features of chaotic signals in secure communication systems were studied. The system under consideration was based on a third-order Phase-locked Loop (PLL), and consists of a transmitter and receiver driven by a common chaotic signal. Mathematical differential equations representing the system were derived and then simulated using Matlab®. It was found that a one-to-one synchronisation occurs when the transmitter and receiver are identical and have the same initial conditions. On failure to satisfy these conditions, it was impossible to recover the information signal from the transmitted signal.     

Chaotic Communication Based on the Particle-in-a-Box Electronic Circuit

A secure communication system based on the error-feedback synchronization of the electronic model of the particle-in-a-box system is proposed. This circuit allows a robust and simple electronic emulation of the mechanical behavior of the collisions of a particle inside a box, exhibiting rich chaotic behavior. The required nonlinearity to emulate the box walls is implemented in a simple way when compared with other analog electronic chaotic circuits. A master/slave synchronization of two circuits exhibiting a rich chaotic behavior demonstrates the potentiality of this system to secure communication. In this system, binary data stream information modulates the bifurcation parameter of the particle-in-a-box electronic circuit in the transmitter. In the receiver circuit, this parameter is estimated using Pecora-Carroll synchronization and error-feedback synchronization. The performance of the demodulation process is verified through the eye pattern technique applied on the recovered bit stream. During the demodulation process, the error-feedback synchronization presented better performance compared with the Pecora-Carroll synchronization. The application of the particle-in-a-box electronic circuit in a secure communication system is demonstrated.     

Improved auxiliary particle filter‐based synchronization of chaotic Colpitts circuit and its application to secure communication

In this paper, we propose a synchronization scheme based on an improved auxiliary particle filter (IAPF) for chaotic Colpitts circuit and conduct an experimental study on the synchronization performance with application to secure communications. Specifically, with the synchronization scheme, when the chaotic signals generated by an analog Colpitts circuit are transmitted through a nonideal channel, the distorted signals are processed digitally by the novelly designed IAPF at the receiver, in order to obtain the synchronized signals of the transmitter circuit. Experimental results indicate that synchronization can be achieved over both the additive white Gaussian noise channel and the multipath fading channel with low signal‐to‐noise ratio, even if there exist severe circuit parameter mismatches between the transmitter and the receiver. Furthermore, a chaos‐masking secure communication system is constructed and verified over both the additive white Gaussian noise channel and the multipath fading channel, and the bit error rate is evaluated versus different signal‐to‐noise ratios and symbol periods. It is shown that the achievable bit error rate can reach the order of magnitude of 10 ^{− 4} without error correction coding techniques. In addition, security analysis demonstrates that the proposed chaotic secure communication system is resistant to the brute‐force attack. Copyright © 2013 John Wiley & Sons, Ltd.     

Robust Chaotic Communication Based on Indirect Coupling Synchronization

This paper proposes a chaotic communication approach using indirect coupled synchronization scheme with high power encrypted signals. The proposed scheme is carefully designed so that the encrypted signal does not deteriorate the synchronization unlike in traditional communication methods. The synchronization problem is solved using observer-based controller. The advantages of this approach are the general and systematic feedback observer design methodology suitable for convergence rate of synchronization; flexibility in selection of chaotic signals for cryptosystem secure key generator; and improvement of the frequency-domain characteristics of the transmitted message. Computer simulations show that the synchronization between the transmitter and the receiver is more robust for different amplitude values of the information signal, even in the presence of external disturbances.     

Markov-jump-system-based secure chaotic communication

In this paper, a new Markov-jump-system (MJS)-based secure chaotic communication technique is proposed. An MJS evolves by switching from one state evolution model to another according to a finite state Markov chain. The transmitter in the proposed communication system is an MJS consisting of multiple transmission maps, that is, the transmitter switches from one chaotic map to another during the transmission of data. This switching feature makes it difficult to identify and follow the transmission without knowing the transmitter parameters, i.e., to eavesdrop, thereby increasing the security offered by the inherently secure chaotic communication system. If the chaotic maps used at the transmitter, and the corresponding Markov transition probability matrix of the MJS are known to the (authorized) receiver, then a multiple model estimator can be used to track the MJS transmitter. In this paper, the use of the interacting multiple model (IMM) estimator is proposed as part of the receiver to follow the switching transmitter. The effectiveness of the IMM-estimator-based receiver to follow the switching transmitter is evaluated by means of simulations. A new modulation technique that uses the MJS transmitter is also introduced. Further, it is shown that the same receiver framework, when used as a receiver for chaotic parameter modulation, provides significant performance improvement in terms of bit-error rate compared to a receiver that uses extended Kalman filter. In addition, the seemingly more complex IMM-estimator-based receiver is shown to significantly reduce the computational complexity per transmitted bit, thus resulting in increased data rate.     

基于Lorenz超混沌系统模糊渐近同步的保密通信系统

研究了一种基于Lorenz超混沌系统渐近同步的保密通信系统设计方法。首先采用T-S模糊模型对Lorenz超混沌系统进行精确描述,进而基于模糊混沌同步理论,利用Lorenz超混沌系统设计信号发射器和接收器,实现混沌保密通信。最后利用Matlab软件进行仿真研究。     

A second-order Markov model to synchronize a quasi-chaotic sequence: application of synchronization and decoding problem with belief propagation

The use of chaotic codes in transmission systems presents many advantages, not only in term of security, but also to combat multi-path propagations and to allow multiple access. Nevertheless, the main problem of communication with chaos is the design of an experimental and real-time synchronization decoder between transmitter and receiver. In this paper, we suggest to use the belief propagation algorithm as a new approach for synchronizing quasi-chaotic signals. In this approach, the transmitter contains a digital chaotic oscillator which is perturbed by the information signal. The receiver consists in a dual system augmented with a belief propagation processing, whose aim is to recover the information signal. We suppose that the channel is Gaussian and synchronization is forced in a first step. Once synchronization is achieved, the information signal modulated the chaotic system and is transmitted on the Gaussian channel. An adaptative belief propagation algorithm is processed to recover the signal information.