基于分块置乱与扩散的分数阶混沌彩色图像加密算法

A New Color Image Encryption Algorithm Based on Image Block Permutation and Diffusion with Fractional-order Chaos

提出一种基于分块置乱与扩散的分数阶混沌彩色图像加密算法.首先,将彩色明文图像转换为由各基色分量组成的灰度图像,并将其划分成若干块;然后,利用Logistic映射产生的一组随机整数,对该灰度图像进行分块置乱,得到置乱后的彩色图像;最后,将置乱图像的每个基色分量均分成两个子块,并利用优化改进后的分数阶混沌序列,以并行方式对子块进行两轮像素值的改变及扩散操作,从而得到最终的加密图像.理论分析和实验结果表明,该算法具有加密速度快、安全性高、加解密效果好等优点,并能抵抗差分攻击、统计攻击和选择密文攻击等.

A new color image encryption algorithm is proposed based on image block permutation and diffusion, using the fractional-order chaotic system. First, the color plain image is converted into a gray-scale image, which is composed of the R, G, B components of the plain image, and then we divide the gray-scale image into blocks. Secondly, the position of each image block varies according to a Logistic map. Finally, each component of the scrambled image is decomposed into two blocks, and the image pixels＇ values are modified and diffused simultaneously in a parallel manner with two rounds using the improved fractional-order chaotic sequences. Thus we obtain the cipher-image. Theoretical analysis and experimental results show that the presented encryption algorithm has fast speed, high security, good encryption/decryption effects, and can resist differential attack, statistical attack and cipher-text attack.