基于混沌的话音保密单元的设计

在DSP(Digital Signal Processor)平台上构建了基于混沌的嵌入式语音保密单元。通过分析Logistic混沌映射的特点,给出了基于对Logistic混沌映射变量和参数同步扰动的新的混沌序列的产生方法。提出了使用该混沌序列的流密码加密方案并以DSP为硬件平台,采用模块化设计,通过基本电路和扩展电路并辅以相应的软件设计实现话音保密通信功能,设计了标准串行接口使之可同多种语音通信终端连接,具有很高的安全性和广泛的实用性。     

改进混沌方程及其在保密VoIP系统中的应用与实现

传统二维Henon混沌映射由于复杂度低、混沌区间小,在应用于加密算法时存在安全隐患。针对这一问题提出了一种改进型Henon映射,相较传统映射混沌区间提升了82.35%,复杂度提升了60.8%,更加适用于混沌保密通信系统的设计。在ARM平台上,基于改进型Henon映射设计实现了一种保密通信系统。其中,加密端由音频编解码芯片产生明文数字话音信号,主控芯片使用二值混沌序列对其进行流密码加密,并通过以太网芯片完成密文话音在IP网的传输,解密端在帧同步后通过逆过程实现话音回放。实现结果表明,在计算精度范围内系统对密钥敏感性强,加密前后话音信号统计相关特性低于0.3,保密效果较好。     

一种多级混沌调制保密通信系统

针对单级混沌通信系统安全度不高的局限性的情况,提出一种用环形蔡氏电路实现多级混沌调制的保密通信系统方案．该方案的主要特点是首先,采用多级混沌调制,提高了整个系统的安全性能;其次,环形蔡氏电路具有两个独立可调的分岔参数电阻,起到了密钥参数的作用,进一步增加了对信号破译的难度．     

半导体激光器混沌双向保密通信系统理论研究

提出外部光注入半导体激光器激光混沌全光耦合-反馈同步系统，进行激光器系统稳定性动力学分析并计算出最大Lyapunov指数，导出系统的同步误差扰动方程以及系统有混沌隐藏编码时的同步误差公式和解调公式，数值证明并模拟实现了系统的混沌同步，分析同步瞬态响应和噪声影响，该系统具有较强的抗干扰能力。模拟具有正弦调制信号的调制频率0．2GHz混沌模拟通信和数字信号调制速率0．2Gb／s的混沌数字通信以及调制速率0．05Gb／s混沌键控通信的应用，特别分析了系统解码特性和调制带宽，系统无论是在时域还是在频域，都具有非常好的保密性，该系统可以作为混沌双向保密通信使用。研究表明系统准许在一定范围内可以有参数失配，系统的实际应用是有可能的。     

Logistic混沌映射性能分析与改进

混沌系统是基于混沌的数据加密领域的一个重要研究对象,Logistic混沌映射是最简单和有效的混沌系统,被广泛应用在大多数混沌加密算法中,Logistic映射的安全性成为研究的热点。针对Logistic序列存在的吸引子与空白区问题,该文提出一种基于初始值和分形控制参数之间关系的Logistic映射改进方法。利用两者之间关系对映射自变量区间进行合理分段,扩大了混沌控制参数区域,将满射范围扩大到整个控制参数区间,使产生的序列分布更均匀,解决了稳定窗与空白区等问题。通过将改进Logistic与其它分段Logistic映射进行仿真对比,实验结果表明改进后的映射产生的序列混沌特性得到显著加强,分布更均匀,具有更好的随机性能测试指标。另外,改进Logistic映射计算复杂度低,实现简单,在扩频通信与混沌密码等领域有广阔的应用前景。     

基于余幂-激活离散超混沌加密的多参数加权分数傅里叶变换安全通信方法

为提高物理层安全传输性能,该文提出一种新的基于2维余幂-激活(2D-CPA)离散超混沌加密的多参数加权分数傅里叶变换(MP-WFRFT)安全通信方法。首先,将激活函数和余弦函数作为非线性因子引入1维立方(cubic)混沌映射,构造2维混沌映射。非线性因子可对原始cubic混沌映射的迭代过程进行扰动,从而获得更加饱满的相轨。利用分岔图、相图、Lyapunov指数谱等对提出的2维混沌映射动力学特性进行了验证。结果表明,构造的2维混沌序列随机性良好,可进入超混沌状态。然后,利用余幂-激活离散超混沌序列分别构建幅度变换矩阵、相位旋转矩阵和MP-WFRFT参数池,完成对星座幅相加密,以及MP-WFRFT动态变换加密过程,进一步消除数据统计特征,同时提升MP-WFRFT变换的抗参数扫描性能。数值仿真结果表明,加密数据的星座图呈类高斯分布,且传输系统对密钥的敏感性良好。     

基于多层密钥的混沌映射保密通信系统

 针对低维映射安全性的弱点,提出一种混沌遮掩保密通信的改进方案.该方案利用分层的两级密钥管理体制,将加密用的混沌序列改为动态参数,在提高密文安全性能的同时,不降低加密速度和传输速度.论证表明,低维映射仍有很好的应用潜力.     

Improving the Security of Chaotic Synchronization With a $Delta$-Modulated Cryptographic Technique

A secure chaos-based communication with a $Delta$-modulated chaotic cryptographic technique is developed in this paper. We prove that a $Delta$ -modulated feedback control of a 1-D discrete-time control system gives rise to a chaotic system. Base on this chaotic system, a modified parameter modulation scheme is proposed to improve security. As illustrated by numerical simulation, the parameter in the sender is protected by a secure cryptosystem against two popular attacks.      

基于神经网络与复合离散混沌系统的双重加密方法

正交频分复用(OFDM)已被广泛应用于无线通信系统,其数据传输安全具有一定的实际意义。该文提出了一种双重加密方案,采用神经网络生成置乱矩阵实现第1次加密,通过基于Logistic映射与Sine映射的复合离散混沌系统产生的混沌序列进行第2次加密。该双重加密方案极大提升了OFDM通信系统的保密性,可以有效地防止暴力攻击。相比于单一的1维Logistic映射的混沌系统,基于Logistic映射与Sine映射的复合离散混沌系统具有更大的密钥空间。该文运用Lyapunov指数与NIST测试验证了该混沌系统的混沌特性及随机性,并仿真验证了双重加密方案的保密性能。仿真结果表明,该文所提出的加密方案密钥空间为4×1093,Lyapunov指数提高到0.9850,NIST测试中最大P值为0.9995。该双重加密方案可在不影响传输性能下极大提升OFDM通信系统的安全性。     

一种Logistic密钥及其性能分析

混沌系统是一种高复杂度的非线性动态系统,具有对初始条件和混沌参数非常敏感性,以及生成序列的非周期性、宽噪声特性和伪随机性,非常适合保密通信领域。利用Logistic映射并结合混沌加扰方法,构建一种混沌密钥序列,并对构建的混沌密钥序列进行了性能分析。分析和仿真结果表明,构建的密钥序列具有良好的随机性和初值敏感性。     

基于单片机的彩色图像混沌保密通信

图像加密技术广泛应用于信息安全领域,并且在无线通信及互联网安全方面尤为重要。基于混沌保密通信原理,在单片机上采用CNN（细胞神经网络）,实现了彩色图像的混沌保密通信。首先把彩色图像数据嵌入到混沌信号当中,然后在接收端根据混沌同步原理解出图像数据。给出不同噪声参数和同步参数时的实验结果,并对结果作简要讨论。     

一种新的基于被扰动的Lorenz系统的混沌加密算法

提出一种基于被抚动的Lorenz系统的加密算法.首先通过Legendre多项式对Lorenz系统中的系统参数b进行扰动,然后再利用Lorenz产生的随机序列对原文信息进行一系列的操作变换,使得加密的信息更加安全.通过扰动有效的补偿了计算机有限精度导致的混沌系统退化行为,经对本算法的模拟实验及详细性能分析,结果表明该加密...     

基于混沌序列的视频保密通信

随着网络和多媒体技术的快速发展,信息安全技术成为了人们关注的一个热点课题。图像视频信息保密通信是混沌应用的一个新领域,混沌加密在计算机网络和视频通信方面的应用为解决信息安全问题开辟了一种新的途径。根据一个离散时间混沌序列,运用驱动—响应式同步方法对视频数据进行实时加密和解密,最后通过Wi Fi网络传输实现了无线混沌视频保密通信。     

A fast encryption algorithm of color image based on four-dimensional chaotic system

As the low complexity of low-dimensional chaotic system and the slow speed of image encryption, this paper proposes a fast encryption algorithm of color image based on four-dimensional chaotic system. Firstly, we propose a new method of designing four-dimensional chaotic system based on the classical equations of three-dimensional chaotic system, to increase the complexity and key space of the encryption algorithm. Secondly, according to the nature of color images’ pixels channel, we design a new pseudo-random sequence generator and reuse the random sequence, to improve the speed of image encryption. Finally, the methods of row-major and column-major are used to diffuse the original image and the cat map with parameter is used to scramble the image pixels, respectively, to achieve the effect of encryption. The results of simulation and security analysis show that the proposed encryption algorithm is of good performance on security, robustness and high encryption speed.     

一种基于超混沌Mackey-Glass系统的语音加密算法

针对低维混沌序列加密语音信号保密性较差,而复合混沌序列加密信息又使得混沌系统难以用软硬件实现的问题,研究了一种基于参数辨识的超混沌时滞模型的加密算法.该算法引入了分块加密的思想,采用了一种映射的方法产生密钥,不仅实现简单,实用性强,而且有效地改善了由于计算机有限精度效应而产生的混沌周期行为,增强了保密性能.     

Chaotic communication systems in the presence of parametric uncertainty and mismatch

A recently developed synchronization scheme in (Phys. Lett. A 2007; 361 :108–114) is applied to design a secure communication system with parametric uncertainties and mismatches in this paper. Based on the bounds of the uncertainties and mismatches and a pre‐specified bound of the synchronization error, a scheme is given to determine an upper bound of impulsive intervals. With the scheme, the synchronization error is ensured to approach to and stay within the given pre‐specified bound and this in turn guarantees that signals can be decoded accurately. To further enhance system security, it is also proposed to transmit functions of the chaotic states at impulsive instants, instead of the states directly. The designed system is tested and verified with text, audio and image encryption and transmission with comparisons to some existing schemes. Copyright © 2008 John Wiley & Sons, Ltd.     

基于混沌参数调制的数据加密算法

讨论了攻击混沌参数调制保密系统的两种策略,在此基础上提出一种两级调制的混沌映射数据加密算法,其中给数据又增加了一层反破解的混沌保护外壳.该方案生成的密文序列具有很强的复杂性,能隐藏参数数字调制的特征.在分析数据加密的过程中给出了仿真结果.     

Secure communication with a chaotic system owning logic element

In recent years, various chaotic systems have been introduced in literature to be used in different branches of science. In the field of secure chaotic communication, more complex chaotic systems are proposed, such as high dimensional (4D, 5D), multi-scroll, surface equilibrium point, to enhance communication security level. In this study, a chaotic system owning logic element is used for increasing the level of security of chaotic communication system, which has not been previously implemented for this purpose in the literature. The used chaotic system includes signum functions, maximum function and absolute operation term. Also, there are analog devices and digital device in the electronic circuit of this chaotic system. These properties increase the complexity of the chaotic system and the security level. Sliding mode control method is preferred for the synchronization part of the secure communication. In this regard, numerical analysis and electronic circuit design of the secure chaotic communication system by using the chaotic system owning logic element have been performed successfully.     

关于数字混沌系统保密通信的探讨

本文对D.R.Frey(1993)提出的基于非线性递归数字滤波器的混沌保密通信系统的参数选取、适用条件、抗噪声能力以及保密能力等进行了分析,并采用混沌密码序列来提高该通信系统的保密性。模拟结果表明,该系统具有一定的可靠性和保密性,而且结构简单、容易实现。     

A hybrid chaotic map for communication security applications

Recently, the synchronization between two matching chaotic systems to provide confident communication has gained a lot of interest. Continuously, there is a necessity to produce a novel dynamical system to be used in synchronization to implement a strong security system. In this paper, a hybrid chaotic system is suggested and verified for the potential use of secure communication through chaos synchronization. The Lyapunov exponent (LE) and zero‐one (0‐1) tests have been used to verify the performance of the suggested hybrid chaotic system, while National Institute of Standard and Technology (NIST) tests have been applied to verify the randomness properties. And the synchronization has been achieved between master and slave systems by using nonlinear control laws. The simulation outcomes demonstration that the hybrid system has chaotic performance and outstanding randomness characteristic. The statistical results gained for LE test was 0.8822, and for frequency test (FT) was 0.2028, while for the run test (RT) was 0.1924. Accordingly, the suggested hybrid system can be used to evolve functional synchronization algorithms and encryption for image, video, and voice secure communication applications.