In view of the feature of digital image and on the basis of compound chaos, an images encryption algorithm is proposed. Firstly, it divides the image into two halves. One half has the four high bits,and the other has four low bits. Secondly, under the control of compound chaos, it scrambles positions of pixels, replaces pixels, and diffuses pixels in the two halves respectively. Thirdly, it combines the two halves correspondingly to get an image with 8 bits per pixel, then repalces and diffuses 8-bit pixels. After iterating the two upper procedures 2 times, the cipher-text is obtained. Theory analysis and experiments show that the algorithm is convenient to realize in parallel, takes strong sensitivity with huge key space, conforms to confusion and diffusion principles of cryptography, and gets high security.%针对数字图像的特点,在构造复合混沌系统的基础上提出一种加密算法:首先将4个高比特位和4个低比特位拆开形成2个新的图像,新图像中每个像素只有4比特；然后利用复合混沌系统分别置乱这2个新图像中像素的位置,并分别对它们进行替换和扩散；再后将高、低平面的数据对应组合形成8比特每像素的图像,并用混沌序列中后续的数值对8比特的像素进行代换和扩散.如此迭代2轮,最后得到密文图像.理论和实验结果表明该算法具有易于并行实现的特性,密钥空间大,敏感性强,符合密码学的混淆、扩散原则,安全性高.
展开▼
