基于四维超混沌系统的彩色图像加密算法

针对彩色图像在加密过程中数据量大、相邻像素相关性强及冗余度高等缺陷,提出基于新四维超混沌的彩色图像加密算法.利用混沌性能更好的四维超混沌系统与反向传播神经网络结合进行序列融合运算,生成伪随机性更好的融合序列作为密钥流;利用密钥流对彩色图像像素块进行位置置乱及像素扩散运算,得到最终的密文图像.仿真计算结果表明,该加密算法...     

基于三维混沌系统的图像加密算法

为了改进图像加密算法的安全性和效率,提出了一种基于三维混沌系统和位运算的数字图像加密算法,利用三维混沌序列的坐标分量分别产生置换序列和二值序列,在对待加密图像进行预处理的基础上,先应用混沌置换序列对预处理的结果图像进行基于灰度值位序列的置换操作,然后再应用产生的二值序列对结果图像的灰度值位序列进行位异或加密运算。实验结果表明,该算法具有良好的安全性和加密效果。     

复合级联混沌的彩色图像加密算法

分析了目前基于混沌系统的彩色图像加密算法,其中发现在混沌彩色图像加密过程中安全性方面的不完善,并在此基础上提出了一种新型的基于级联混沌的多重像素置乱彩色图像加密算法。该算法采用了Kent-Logistic的级联混沌与Henon离散混沌的复合系统,同时结合Arnold映射和像素排列切割的多重像素置乱方法,使得图像像素值和像素位置全盘置乱扩散,从而达到明文图像信息完全隐藏的密文效果。仿真实验表明,该算法不仅能有效抵抗选择明文（密文）攻击、统计特性分析、差分攻击,而且还具有加密效果好、密钥空间大等优点。     

A Novel Image Encryption Algorithm Based on Hybrid Chaotic Mapping and Intelligent Learning in Financial Security System

With the expansion and prevalence of financial certification, problems of financial security have been springing up. How to ensure the security of financial information and protect our privacy is an issue of particular concern. In order to reduce the influence of chaotic periodicity on cipher-text, an image dynamic encryption algorithm based on hybrid chaotic system and deep network is proposed in this paper. Firstly, the hybrid chaotic system is constructed to combine many mapping functions by using the nonlinear combination mechanism, and the chaotic sequence is outputted to generate the initial value of hybrid chaotic system by using the pixel value. Then the plain-text pixel values are adopted to generate the initial value of the hybrid system for improving the anti-plain attack ability of the algorithm; Artificial neural network is used to process chaotic sequences, and effectively eliminate chaotic periodicity; The classification and encryption of permutation image are realized by constructing quantization method and hetero-diffusion technology. The experimental results show that our proposed encryption technology has higher security and stronger ability to resist plain-text attack compared with the existing image encryption algorithms, which adapts to enhance the security of the financial system.

     

基于分数阶统一混沌系统的图像加密算法

为了解决数字图像信息传输所面临的安全性问题,基于分数阶统一混沌系统,提出了一种新的图像加密算法.采用经典的置乱-扩散机制,整个加密策略分为图像像素位置置乱和像素值替代两个过程.在像素置乱的过程中,采用排序的方式分别对图像的行和列进行置乱.在像素值替代的过程中,通过与密钥序列进行异或运算来实现加密.而混沌系统则作为伪随机序列发生器,并作用于加密的各个阶段.安全性和时间复杂度分析表明:该算法具有高的安全性和低的时间复杂度,且能够抵御几种常见的攻击方式.     

基于混沌映射的图像Contourlet编码加密算法

针对图像Contourlet多级树集合分裂编码的安全性问题,利用混沌密码设计了一种新的图像加密算法。使用具有良好随机性、安全性的混沌映射构造置乱数组和混沌密钥流对图像进行加密,由两个步骤组成：基于有序扫描表的快速置乱算法;基于编码扫描输出比特的异或加密算法。经实验验证,该算法能对图像视觉内容达到良好的掩密效果,具有密钥敏感度高、加密速度快、安全性高的优点。     

基于最小粒度全置乱的图像加密算法*

依据混沌置乱信息熵, 给出选择驱动图像比特全排列混沌映射的准则,依据混沌轨道的不可预测性,设计一个图像比特全置乱算法,应用选择的混沌完成图像最小粒度—比特全空间内最大程度的等概率置乱。为增加抗攻击能力,又根据混沌映射拉伸折叠机理,设计图像像素替换算法完成图像加密变换;分析算法密钥空间、密文数字特征、相关性、抗差分攻击能力。结果表明,该图像加密算法较Ye算法和Huang算法具有更好的置乱度、去相关性和抗差分攻击能力,能够更加有效地保护数字图像。     

A new design of cryptosystem based on S-box and chaotic permutation

In this paper, we present a new design of cryptosystem characterized by an optimized substitution box (S-box) and random permutation. Our proposed S-box is generated using a modified genetic algorithm. The crossover process is performed with sophisticated research using the best previous population. We use randomness and ergodicity of the logistic map to add complexity and robustness to our proposed method. Many tests proving the nonlinearity of our S-box have been carried out to demonstrate the efficiency of our algorithm. In the second part, we offer a new permutation algorithm based on a chaotic sequence generated from the logistic map. To show the performance of our proposition, we compare our results with previous algorithms. The results of its statistical analysis, like entropy value and correlation between adjacent pixels, show that the proposed image encryption scheme provides security for image encryption. The time speed of the proposed algorithm confirms the possibility of real-time implementation.

     

一种基于交叉混沌序列的图像加密算法

当前研究的混沌加密算法大都是基于单级混沌系统或低维的混沌加密技术,而这些混沌映射的密钥空间太小,可以轻易地被破译,它们还不算具有严格密码学意义上的保密性。文中提出了一种利用Logistic映射与Chebyshev映射作为2个混沌发生器的算法,在这种交叉混沌映射的图像算法中,不仅通过加密矩阵对图像像素进行灰度置乱,而且根据离散映射生成相应的符号矩阵和置换矩阵。实验结果证明了该算法实现简单,计算量小,且图像的解密结果对混沌序列的初始值有较强的依赖性,安全性高,同时也证明了给出的图像置乱度能更好地反映图像加密前后的视觉差别和加密效果。     

Symmetric keys image encryption and decryption using 3D chaotic maps with DNA encoding technique

In present digital era, multimedia like images, text, documents and videos plays a vital role, therefore due to increase in usage of digital data; there comes high demand of security. Encryption is a technique used to secure and protect the images from unfair means. In cryptography, chaotic maps play an important role in forming strong and effective encryption algorithm. In this paper 3D chaotic logistic map with DNA encoding is used for confusion and diffusion of image pixels. Additionally, three symmetric keys are used to initialize 3D chaos logistic map, which makes the encryption algorithm strong. The symmetric keys used are 32 bit ASCII key, Chebyshev chaotic key and prime key. The algorithm first applies 3D non-linear logistic chaotic map with three symmetric keys in order to generate initial conditions. These conditions are then used in image row and column permutation to create randomness in pixels. The third chaotic sequence generated by 3D map is used to generate key image. Diffusion of these random pixels are done using DNA encoding; further XOR logical operation is applied between DNA encoded input image and key image. Analysis parameters like NPCR, UACI, entropy, histogram, chi-square test and correlation are calculated for proposed algorithm and also compared with different existing encryption methods.

     

基于混沌和比特级置乱的并行图像加密算法

文章提出一种基于混沌和比特级置乱的并行图像加密算法--CBLP算法。该算法主要包含3种基本运算：像素位置置换、比特旋转（BR）以及像素值异或（XOR）运算,其中位置置换用于置乱像素位置,BR和XOR运算用于扩散图像的像素值。另外,为充分利用当前异构处理平台的计算资源以大幅提升算法的执行效率,文章在NIVIDIA GeForce GTX 580 GPU上使用OpenCL技术并行实现了该算法。实验结果和数值分析表明,CBLP算法具有较高的加密效率和良好的安全性,可以有效地应用于实际加密当中,具有较高的应用价值。     

A chaotic framework and its application in image encryption

A novel image encryption framework is proposed in this article. A new chaotic map and a pseudorandom bit generator are proposed. Apart from this, a novel image encryption system is designed based on the proposed map and the proposed pseudorandom bit generator. These three are the major contributions of this work that makes a complete cryptosystem. The proposed new chaotic map is proposed which will be known as the ‘RCM map’ and its chaotic property is studied based on Devaney’s theory. The proposed pseudorandom bit generator is tested using the NIST test suite. The proposed method is simple to implement and does not involve any highly complex operations. Moreover, the proposed method is completely lossless, and therefore cent percent of data can be recovered from the encrypted image. The decryption process is also simple to implement i.e. just reverse of the encryption procedure. A scrambling algorithm is also proposed to further enhance the security of the overall system. The simulation, detailed analysis, and comparative studies of the proposed overall image encryption framework will help to understand the strengths and weaknesses of it. The experimental results are very promising and show the prospects of chaos theory and its usage in the field of data security.

     

一种小波神经网络的混沌加密算法研究

概括了小波神经网络的主要理论,将小波神经网络和混沌系统相结合,建立了一种混沌序列的生成模型,给出基于小波神经网络的混沌加密算法,最后对算法进行计算机仿真实验.结果表明小波神经网络具有更快的收敛速度和更准确的逼近能力,而基于小波神经网络的混沌加密算法具有很高的安全性.     

基于比特置换与核酸序列库的混沌图像加密算法

提出了一种基于比特置换与DNA序列运算的混沌图像加密的算法。该算法首先利用Chen系统产生混沌映射索引对图像进行像素位置置乱,结合蝶形网络对比特位置乱,以实现位级别置乱。再对图像进行DNA编码,并与核酸序列进行代数运算,实现像素的替代,进一步提高了加密的安全性。最后通过密文反馈来进一步增强算法的混淆和扩散特性。实验和安全性分析结果表明,该算法不仅密钥空间大、对密钥的敏感性强,而且能有效抵御统计性分析和穷举分析等攻击操作。     

基于混沌序列的通用数字图像加密算法

为有效保护数字图像的信息,提出一种基于混沌序列的通用的数字图像加密算法。先根据密钥及图像大小产生一个混沌序列,然后根据子密钥及图像类型将其转换为无符号整数序列,最后再依次与对应的像素值进行异或运算以实现置换加密。应用评价指标对加密效果与安全性进行分析。理论分析与实验结果表明,该算法密钥空间大,具有良好的加密效果、安全性与统计特性,且抗干忧能力较强。     

整合神经网络置乱图像的动态自反馈混沌系统图像加密

目的 针对当前大多数数字图像加密算法多采用单一的混沌系统,且置乱方法基本只采用像素行列互换、Arnold变换、Baker变换、序列排序构造替换表等几类,提出一种新的整合神经网络置乱图像的动态自反馈混沌系统图像加密算法。方法 该算法通过1维Logistic混沌、chebyshev混沌和自定义m（x）运算构造了一种动态自反馈混沌系统,通过频数检测、序列分布图、平衡度分析、相关性分析、Lyapunov指数验证了系统的随机性,并对其序列进行了均匀化处理,通过序列均匀性证明、序列分布图、序列期望和方差验证了均匀化效果。该算法从混沌序列中随机选取输入值和参数输入神经网络,采用每组神经网络输出值构造置乱矩阵进行初次全局置乱,再从bit位进行二次置乱;采用两组与明文相关的秘钥序列进行像素值替代扩散,使得明文到密文经过中间密文变化,增强了算法的安全性。结果 通过计算机仿真和性能分析表明该加密算法体现了良好的密码学特征,从秘钥空间、秘钥敏感性、统计分析、信息熵、差分分析、相邻像素相关性分析各方面验证了其安全性,数据表明该算法秘钥空间达到了2²¹⁶,信息熵为7.998 3,水平、垂直、对角方向相邻像素相关系数分别为-0.000 381、0.000 607、-0.000 309,NPCR值介于（0.995~80.996 6）之间,UACI值介于（0.333~0.338）之间。结论 该算法可以实现良好的加密效果,在数据对比上优于超混沌系统图像加密、像素位置和bit位双重置乱加密等,可以被广泛应用在灰度图像加密中乃至扩展到彩色图像加密中,能够起到图像信息在网络传输、存储中的隐私保护作用。     

一种基于混沌序列的加密算法设计

加密是保证敏感信息安全的重要手段。该文设计了一种基于混沌序列的加密方法。该方法以非线性动力系统的Logistic映射为模型,采用线性同余法生成序列参与融合扰动,解决混沌有限精度问题。加密算法中,引入明文长度作为控制参数,控制混沌及线性同余的初始循环次数,使密钥流与要加密的明文相关,增加密钥流的复杂性和随机性,抵御混沌重构攻击,进一步增加安全性。实验结果表明,该算法能够得到令人满意的效果。     

A new chaos-based fast image encryption algorithm

In recent years, various image encryption algorithms based on the permutation–diffusion architecture have been proposed where, however, permutation and diffusion are considered as two separate stages, both requiring image-scanning to obtain pixel values. If these two stages are combined, the duplicated scanning effort can be reduced and the encryption can be accelerated. In this paper, a fast image encryption algorithm with combined permutation and diffusion is proposed. First, the image is partitioned into blocks of pixels. Then, spatiotemporal chaos is employed to shuffle the blocks and, at the same time, to change the pixel values. Meanwhile, an efficient method for generating pseudorandom numbers from spatiotemporal chaos is suggested, which further increases the encryption speed. Theoretical analyses and computer simulations both confirm that the new algorithm has high security and is very fast for practical image encryption.     

改进混沌方程及压缩感知理论图像加密算法

针对传统Logistic混沌系统混沌性能低,生成伪随机序列随机性较差等问题,本文提出一种新的改进Logistic混沌方程,并与Lorenz超混沌系统、压缩感知理论相结合构建一个多混沌图像压缩加密系统。在加密过程中与传统加密算法相结合,进行置乱、扩散操作最终获得密文图像。通过改进的Logistic混沌方程获得随机性能更好的伪随机序列来构造受控测量矩阵,仿真实验表明通过改进的Logistic混沌方程来构造的受控测量矩阵在压缩率为75%的条件下峰值信噪比达到34.26 dB,与传统Logistic混沌方程相比在同等条件下提高约10 dB,并且该算法有较好的抗差分攻击性能,像素改变率（NPCR）与统一平均变化程度（UACI）接近理论值。故本文提出的加密算法具有较好的压缩性、安全性以及信号重建特性。     

混沌映射与比特重组的图像加密

目的 当前很多图像加密都采用基于比特的加密算法。针对这种比较流行的加密算法所存在的安全缺陷问题,提出一种能够解决比特面0比特和1比特置乱时的位置限制的图像加密算法,实现比特的全局重组。方法 首先利用Tent混沌映射生成一个伪随机序列,然后利用生成的伪随机序列对比特明文图像进行整行以及整列的置乱,将置乱后的比特像素矩阵分块分别进行Henon映射的置乱,最后经过扩散操作得到最后的密文图像。结果 加密后明文图像的像素值的分布由不均匀变成了均匀分布,明文图像的各像素间的相关性被打破,使得原图没有了统计特性,像素变化率（NPCR）以及归一化平均变化强度（UACI）皆接近理想值,算法能够抵抗穷举攻击和差分攻击,并且在能保证加密安全的同时能有较低计算复杂度。结论 本文所提出的图像加密算法具有加密后像素相关性低、密钥空间大,以及对明文图像和密钥高度敏感等特点,本文算法在进行比特级的置乱时,又加入了与明文相关的特性,增强了加密算法的明文敏感性,同时也加强了加密算法的扩散性,可有效地保障密文图像的安全。