基于相位截断菲涅耳变换的彩色图像加密系统

针对相位截断的加密系统无法抵御信息泄露的问题,提出一种基于相位截断菲涅耳变换与随机振幅掩模的加密系统,以抵御信息泄露的问题。将图像分为3个独立的颜色通道,并加入随机幅度掩模通道,对4个通道分别进行菲涅耳衍射截断处理。通过级联处理过程提高了秘钥与密文之间的关联性并消除了信息泄露的风险。最终进行了仿真试验,结果证明,该算法对一般攻击具有较好的鲁棒性,同时解决了信息泄露的问题,优于已有的同类型算法。     

Weak signal detection and adaptive synchronous stability of a novel fifth-order memristive circuit system

This paper is devoted to introduce a novel complex fifth-order memristive circuit system and its applications in synchronous stability and weak signal detection. Firstly, the typical dynamical behaviors of the memristive system are discussed by chaotic phase portrait, complexity analysis, one-parameter bifurcation and Lyapunov exponent spectrum. Secondly, the adaptive control method is applied to realize the synchronization between the drive memristive system (DMS) and the response memristive system (RMS). The results indicate that the synchronization method has strong robustness and anti-interference ability. Thirdly, the weak signal detection of the novel five-dimensional memristive system is realized by using the extreme sensitivity of chaotic system to initial values. Finally, the fifth-order memristive circuit is designed by using basic electronic elements and simulated by Multisim software. And the anti-interference ability and sensitivity of the fifth-order memristive circuit are further verified by adding different weak disturbance signals at different positions of the circuit.     

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.     

基于柱面衍射和彩色空间转换的单通道彩色图像加密

为了解决传统密码系统由于对称特性导致的安全性低的问题,提出了一种新的基于柱面衍射和彩色空间转换的单通道彩色图像加密方法。在加密过程中,首先将彩色图像变换为YCbCr4:2:0格式的单通道图像,然后经过两次柱面衍射和相位截断操作对图像进行加密。在解密过程中,将密钥与密文结合,经过两次柱面逆衍射后重建出彩色原图。由于柱面衍射过程是一个非对称的过程,此算法可以克服基于平面衍射的加密系统的对称特性,将其应用到基于相位截断的加密系统中可以进一步有效提高加密系统的安全性。仿真结果表明,该算法能够有效地对彩色图像进行单通道加密,不仅可以高质量地恢复原始彩色图像,而且加密系统具有较高的安全性。     

A new color image encryption scheme based on DNA encoding and spatiotemporal chaotic system

In this paper, a new color image encryption scheme based on DNA operations and spatiotemporal chaotic system is presented. Firstly, to hide the distribution information of the plain image, we convert the plain image into three DNA matrices based on the DNA random encoding rules. Then, the DNA matrices are combined into a new matrix and is permutated by a scramble matrix generated by mixed linear-nonlinear coupled map lattices (MLNCML) system. In which, the key streams are associated with the secret keys and plain image, which can ensure our cryptosystem plain-image-dependent and improve the ability to resist known-plaintext or chosen-plaintext attacks. Thereafter, to resist statistical attacks, the scrambled matrix is decomposed into three matrices and diffused by DNA deletion-insertion operations. Finally, the three matrices are decoded based on DNA random decoding rules and recombined to three channels of the cipher image. Simulation results demonstrate that the proposed image cryptosystem has good security and can resist various potential attacks.     

超混沌视频加密系统的FPGA设计与实现

随着多媒体技术的不断发展,视频信息安全愈发受到人们的关注。为解决视频信息的安全问题,提出了一种基于现场可编程门阵列(FPGA)技术的超混沌视频加密方法。在加密过程中,一方面FPGA控制数字摄像头实现实时彩色视频信息的采集;另一方面,在计算机密钥指令下,利用FPGA使超混沌系统产生有效的伪随机序列,实现对所采集视频信息的数据和地址的双重超混沌加密。给出了具体的超混沌视频加密算法和设计流程以及FPGA实现结果。安全性分析表明,明密文主观视觉对比显著不同,密钥空间大,视频图像统计特性的相关性弱,说明基于FPGA的超混沌视频加密系统加密效果良好可靠。     

Fusion of confusion and diffusion: a novel image encryption approach

Recently, the development of confidentiality and authenticity ensured by image encryption has been one of the key advancements in the field of secured wireless communication. The proposed work focuses on providing confusion, diffusion and permutation inherently in the system. The input grayscale image is shuffled by employing the Henon algorithm and subsequently separated into 8 bit planes. With the aid of a secret key of 256 bits, chaotic sequences are generated for each bit plane. Later, the logistic map is adapted on the chaotic sequences to obtain the scrambled image. Furthermore, this image is shuffled with Zaslavskii and Hilbert Space Filling Curve algorithms, which establishes the confusion stage. To incorporate the diffusion stage, a self-invertible matrix is generated by a latin square image cipher and a secret key. This matrix and the scrambled image underwent the Hill cipher to build the encrypted image followed by a row-column transformation to ensure multifold security. The proposed compound activities of encryption are successfully implemented on the laboratory virtual instrumentation engineering workbench 2013 platform. Noticeably, the established processes of image encryption are tested in the universal software radio peripheral environment and transceived via an additive white Gaussian noise (AWGN) channel. More specifically, the influence of natural and unnatural (cropping attack) noise on the characteristics of the encrypted image while sharing through AWGN channel has been investigated. Security analysis is performed by computing the unified average changing intensity, number of pixels change rate, correlation value, large key space to defy brute force attack, strong key sensitivity and uniform gray value distribution on encryption.     

HDTV色度空间变换电路的设计与实现

介绍了色度空间变换电路的两种基本实现方法,即模拟方法与数字方法,说明了如何用可编程逻辑器件实现ＨＤＴＶ数字式色度空间变换电路及相应的色差信号滤波,抽取电路,并给出了电路设计的仿真结果。     

一个混沌系统性质分析及其FPGA电路实现

构造了一个新的三维连续自治混沌系统,该系统含有3个参数,2个非线性乘积项通过理论推导、数值仿真、Lyapunov指数谱、分岔图研究了系统的基本动力学特性,还利用FPGA技术设计了一个数字电路,实现三维混沌系统,实验结果与仿真结果完全一致,提出了一种基于FPGA技术实现混沌系统的新方法     

一种数据库加密系统的研究与实现

主要是从数据库管理系统这个层次框架对OS层、DBMS内核层和DBMS外层三不同层次对数据库数据的加密技术进行了简单介绍.通过对数据库和加密技术的研究,确立了基于记录和字段的密钥生成函数.并在最后提出了基于DBMS外层的一种数据库加密系统的实现方案.     

A novel fourth order chaotic system and its algorithm for medical image encryption

Multidimensional Systems and Signal Processing - Today, medical imaging suffers from serious issues such as malicious tampering and privacy leakage. Encryption is an effective way to protect these...     

基于AES加密电路的防复制电路及系统设计

随着各种抄板技术和芯片解剖技术的发展,嵌入式系统芯片正面临着越来越多受攻击风险,如何保护嵌入式系统产品不受非法复制,正日益受到人们的关注,各种防复制方法也应运而生。由此设计了一款软硬件协同的新型防复制电路及系统,用以实现对嵌入式软件版权的保护。防复制电路采用AES加密算法与嵌入式芯片进行多次随机动态加密验证,使破解者无法通过监控通信数据来破解验证保护。防复制电路中内置CPU和安全存储器,用来存储关键数据以及执行部分嵌入式程序,让破解者无法获得嵌入式芯片中完整的程序,从软硬件两方面实现了对嵌入式产品版权的充分保护。本电路在FPGA上进行了实现,并搭建被保护芯片与防复制FPGA电路的联合保护系统,实测结果显示该系统很好的完成了防复制的功能,未通过动态加密验证无法启动系统,此外,没有防复制电路的配合,无法执行完整的嵌入式芯片中的程序。     

一个切换混沌系统的分析与电路实现

采用改变系统乘积项的方法,在已提出的混沌系统的基础上,构建了一个切换混沌系统。分析了平衡点的性质,混沌吸引子相图和Lyapunov指数等特性,设计了可实现切换混沌系统的电路并进行了电路实验,实现结果与仿真结果一致：     

A novel image encryption scheme based on a linear hyperbolic chaotic system of partial differential equations

Compared with general chaotic systems, a linear hyperbolic chaotic system of partial differential equations with nonlinear boundary conditions has larger parameter space, stronger sensitivity to initial condition and control parameter, better random-like behavior and so on, but it has not been employed in cryptography so far. Then using its significant properties, we present a new cryptosystem with coupled map lattices and time-varying delay. The proposed image encryption algorithm with permutation–diffusion architecture can overcome some drawbacks in the existing methods, because the sum of pixel value of original image is used for determining the permutation parameters and the previous cipher image information is utilized in the next diffusion. Theoretical analysis and computer experiments confirm that the new algorithm is efficient, practicable, and reliable, with high potential to be adopted for network security and secure communications.     

Self-adaptive permutation and combined global diffusion for chaotic color image encryption

As to color image encryption, most of the previous algorithms are to encrypt its R, G, B components, respectively, which neglected the correlations among R, G, B components. To overcome this problem, a type of chaotic color encryption scheme was proposed by Wang et al. based on combined permutation and combined diffusion. Unfortunately, there are some drawbacks in the scheme and it has been cryptanalyzed soon. To strength the security performance, a new scheme based on coupled logistic map, self-adaptive permutation, S₈ S-boxes transform and combined global diffusion is proposed in this paper. Simulation results and analyses show that our cryptosystem is immune to some well-known attacks and has high security for practical color image encryption applications.     

四翼超混沌系统的动力学特性分析及其电路实现

为了提高混沌系统的复杂性,本文基于最新提出的简化Lorenz系统,采用正弦函数扰动方法和非奇异变换,设计了一个具有四翼吸引子结构的超混沌系统。通过计算Lyapunov指数、分岔图、相图和Poincaré截面等方法分析了该系统的动力学特性,分析表明该系统具有丰富的动力学行为。采用分立元件,设计了该系统的模拟电路,电路实验结果与数值仿真结果相吻合,为构建具有高性能的混沌保密通信系统奠定了基础。     

线性自调频系统动力学行为分析

为重点研究线性自调频系统的动力学行为,根据锁相环的结构提出了一种新的线性自反馈调频系统,通过对线性自调频系统数学模型的分析,其动力学行为可以用简单的正弦映射描述。文章通过相空间轨迹、分岔图和Lyapunov指数研究正弦映射中的动力学行为和混沌现象,发现其动力学行为具有周期性和对称性的特点。同时分析对比了自调频混沌系统在不同状态下的频谱,为进一步研究自调频混沌信号源的设计和应用提供理论依据和数值参考。     

一种新型的低功耗血糖检测电路设计与实现

针对采用三电极电化学葡萄糖传感器的血糖检测应用,提出了一种新型低功率、低噪声的紧凑式电流测量电路结构。该电路包含一个阈值电压基准电流源结构,能够为电化学反应提供所需的基准电压,并且能够将反应电流转换为响应的电压。采用0.35 μm CMOS工艺进行了具体实现,面积为125 μm×340 μm。采用三电极电化学葡萄糖传感器进行了具体测量,实验结果表明了提出电路的可行性,其功率损耗为0.891mW,产生的噪声为0.73mVrms,适用于便携式电化学血糖检测设备。     

一种数字图像增强系统的设计与实现

数字图像增强处理是根据特定的要求突出数字图像中感兴趣的部分,弱化和除去不感兴趣的内容,它是数字图像处理过程中的重要一环.利用MATLAB软件提供的图形用户界面开发环境和图像处理工具箱,开发了一个面向教学的可视化、开放性、交互性于一体的"数字图像增强系统".实际应用结果表明,该系统运行稳定、操作方便,可移植性和可扩展性强,具有一定的应用前景和较高的实用价值.