基于超混沌系统和动态DNA编码的图像加密

Image Encryption Based on Hyperchaotic Systems and Dynamic DNA Coding

摘要: 基于混沌系统和DNA编码相结合的图像加密是目前研究的热点。针对传统低维混沌系统存在复杂度有限、安全性不足等问题，本文提出一种将超混沌系统和动态DNA编码相结合的彩色图像加密算法。首先，利用明文的哈希值构造混沌系统的初始密钥；然后，通过四维和五维超混沌系统生成的多个混沌序列，对图像像素进行选择、扩散和重组操作。其中，四维混沌系统生成的混沌序列使DNA编码规则动态化，不同的像素值实时选择DNA碱基运算方式；五维混沌系统生成的混沌序列则与DNA编码共同用于图像灰度值的置乱。接着，两个混沌系统生成的混沌序列分别作用于DNA域和像素域，进而完成双重扩散，最后实现图像的加密。根据图像加密的逆过程，可得到解密后的图像。经过实验验证，该算法密钥空间大，复杂度较高，加密效果好。

Abstract: Image encryption based on the combination of chaotic systems and DNA coding is a current research hotspot. To address the limited complexity and insufficient security of traditional low-dimensional chaotic systems, this paper proposes a color image encryption algorithm that combines hyperchaotic systems with dynamic DNA coding. First, the initial key of the chaotic system is constructed using the hash value of the plaintext. Then, image pixels are selected, diffused, and reassembled using multiple chaotic sequences generated by four-dimensional and five-dimensional hyperchaotic systems. The chaotic sequence generated by the four-dimensional chaotic system makes the DNA coding rules dynamic, allowing different pixel values to select DNA base operations in real time. The chaotic sequence generated by the five-dimensional chaotic system is used together with the DNA coding to scramble the image grayscale values. Next, the chaotic sequences generated by the two chaotic systems act on the DNA domain and the pixel domain, respectively, completing double diffusion and ultimately achieving image encryption. The decrypted image is obtained by inversely following the image encryption process. Experimental verification shows that the algorithm has a large key space, high complexity, and good encryption performance.