基于指数复合型混沌系统的图像加密算法

Image encryption algorithm based on exponential compound chaotic system

针对现有基于混沌系统的图像加密算法抗差分攻击能力较弱、混沌系统性能不稳定等问题,提出一种基于指数复合型混沌系统的图像加密算法。该算法首先对图像的R,G,B三个分量插入随机值,由改进的指数复合型混沌系统迭代输出混沌向量构成置乱矩阵,对明文图像进行像素置乱,然后由混沌系统迭代输出的混沌矩阵与明文像素矩阵进行取模运算实现扩散,最后由密钥和混沌序列控制对R,G,B加密矩阵进行矩阵变换,得到密文图像。结果表明:该算法密钥空间大,密文信息熵、像素变化率(NPCR)及归一化平均变化强度(UACI)均接近理想值,抗差分攻击能力强,安全性能高。

Aiming at the problems of existing image encryption algorithms based on chaotic systems,such as weak resistance to differential attacks and unstable performance of chaotic systems,an image encryption algorithm based on exponential composite chaotic systems was proposed.The algorithm first inserted random values into the R,G and B components of the image,and iteratively outputted chaotic vectors from the improved exponential compound chaotic system to form a scrambling matrix,scrambling the pixels of the plaintext image.Then the chaotic matrix output by the chaotic system iteratively and the plaintext pixel matrix were used to realize the diffusion by modular operation.Finally,the ciphertext image was obtained by matrix transformation of encryption matrix of three components of R,G and B,which was controlled by the secret key and chaotic sequence.The results show that the algorithm has a large key space,and ciphertext information entropy,number of pixel change rate(NPCR)and uniform average change intensity(UACI)are all close to ideal values.It has strong resistance to differential attacks and high security performance.