提出一种基于RSA公钥、Arnold置乱变换和混沌加密算法相结合的公开密钥数字图像加密体制，利用客户的公钥对Arnold置乱变换和混沌序列初值进行RSA加密，确保了只有合法用户才能获取置乱参数信息并将图像复原。RSA对参数的加密信息隐藏于图像LSB中，无需另外传递密文，运算简单，具有良好的加密与隐藏效果。

随着对图像加密算法各方面性能的要求持续提高，混沌系统正在朝高维、超混沌不断演进，同时混沌图像加密所涉及的研究范围也越来越广。本文介绍了混沌理论、密码学等基础知识以及混沌系统在图像加密中的应用，研究了混沌图像加密与DNA计算、压缩感知理论的结合，在相关研究成果的基础上，提出两种图像加密算法，并进行了理论分析和Matlab仿真实验。

鉴于传统图像加密技术和低维混沌加密技术各自的局限性,将Lorenz 混沌系统与数字图像置乱技术相结合,设计了一种基于三维混沌系统的数字图像加密算法.首先,对系统输出的实数值混沌序列进行预处理;其次,以此实数值混沌序列直接构造图像置乱索引矩阵;最后,以8×8 块为单位实现数字图像的空域加密,分析与仿真结果表明:预处理后的实数值混沌序列具有更强的伪随机特性,更理想的相关特性;三维混沌系统有更大的密钥空间,使算法具有很强的抗破译性和抗攻击性;系统三维输出的同时利用,可实现三个或多幅图像的并行加密,提高了算法的加

针对传统的图像加密算法，加密策略与待加密图像无关且对像素的置换和混淆往往被拆分为两个耦合性较低的孤立环节所带来的安全问题，提出基于约瑟夫遍历和广义Henon映射的图像比特位加密算法，将待加密图像安全哈希算法1（SHA-1）摘要和用户选定的加密参数联合作为密钥，驱动广义Henon映射对改进的用于位点置换的约瑟夫遍历映射的起始位置、报数间隔和报数方向进行随机扰动，从而使不同的加密图像和加密参数实质对应于不同的位点置换过程，并添加了位点混淆过程以提高位点置换的安全性。实验表明，所提算法可有效地抵抗选择性明文攻击，具有较大的密钥空间和较好的加密性能。

提出一个利用广义Logistic映射构造的二维非线性混沌映射，采用相图、分岔图分析方法，研究该混沌映射的非线性动态特性；利用该二维混沌方程生成混沌序列，将混沌序列进行优化改进，生成密钥序列；采用输出反馈的加密方式，改变图像的像素，达到加密的目的。实验仿真结果表明：该加密算法对明文和密文都非常敏感，混沌序列的选择极其敏感地依赖于明文，有效地提高了抵御选择明文攻击的能力；密文图像信息熵为7.974 3，接近理想值8.000 0，因而加密图像像素具有类随机均匀分布特性；加密图像和明文图像之间的相关性非常小，相邻

本压缩包是我复现的八篇图像加密程序。其中就包括Signal processing、Information scineces、Optik、Nonlinear dynamics、International journal of bifurcation and chaos以及IEEE access等期刊的混沌图像加密算法。

With the increasing requirements of the performance in secure communication filed based on chaos, chaotic systems have been gradually developed into higher dimensions. Because the sequence generated by onedimension chaos, such as Chebyshev map has the problem of weak chaotic properties and uneven distribution, a new two-dimensional chaotic map, called Logistic-Adjusted-Chebyshev map (2D-LACM), is proposed in this paper which enlarges the range of chaotic control parameter, and expands the range of surjection to the entire control parameter interval to make the distribution of the sequence more uniform. Compared with other improved chaotic maps, the proposed 2D-LACM in this paper has more complex chaotic properties and better ergodicity. Next, a visualized image encryption algorithm based on 2D-LACM is proposed (LACM-VIEA), which can encrypt the plain image into a noisy image, and then embed it into a cover image of the same size. In order to demonstrate the security of LACM-VIEA, the algorithm is analyzed in detail from the aspects of key, histogram, visual effect, robustness and anti-plaintext attacks, etc. The final analysis results show that LACM-VIEA has good security performance.

A new two-dimensional chaotic system in the form of a cascade structure is designed, which is derived from the Chebyshev system and the infinite collapse system. Performance analysis including trajectory, Lyapunov exponent and approximate entropy indicate that it has a larger chaotic range, better ergodicity and more complex chaotic behaviour than those of advanced two-dimensional chaotic system recently proposed. Moreover, to protect the security of the crowd image data, the newly designed two-dimensional chaotic system is utilized to propose a visually meaningful image cryptosystem combined with singular value decomposition and Bernstein polynomial. First, the plain image is compressed by singular value decomposition, and then encrypted to the noise-like cipher image by scrambling and diffusion algorithm. Later, the steganographic image is obtained by randomly embedding the cipher image into a carrier image in spatial domain through the Bernstein polynomial based embedding method, thereby realizing the double security of image information and image appearance. Besides, the visual quality of the steganographic image can be improved by the adjustment factor according to different carrier images during the embedding process. Ultimately, security analyses indicate that it has higher encryption efficiency (2 Mbps) and the visual quality of steganography image can reach 39 dB.

图像加密算法与实践：基于C#语言实现_孙燮华著，很好的图像加解密教程，值得学习研究。

以小波变换和双随机相位编码为基本理论依据,提出了一种新的多图像加密算法。该方法利用小波变换的多层次分解特性,提取各个图像的低频部分组合成一幅新的图像,再利用基于混沌的双随机相位编码算法进行加密。所提方法采用低频部分横向叠加的组合方式,避免了加性串扰,提高了系统容量和加密效率。另外,借助混沌系统来生成随机相位模板的思想使得加密系统在减小密钥体积的同时,增加了密钥的敏感性。数值仿真表明所提算法能够有效性的进行多图像加密,并且具有较高的密钥敏感性和良好的鲁棒性。