一种基于猫映射和伯努利移位映射的图像加密算法

An Image Encryption Scheme Based on Cat Map and Bernoulli Shift Map

本文提出了一种基于混沌映射的图像加密算法,采用置乱-扩散的机制对图像进行加密.在置乱阶段,先将大小为M×N的8比特灰度图像拉伸为大小M×2N的4比特灰度图像,然后将4比特灰度图像中k×k的小块作为一个单元,利用混沌伪随机序列进行置乱.为了达到更好的加密效果,笔者对置乱后的图像进行了两轮扩散.对该加密算法进行了安全性能分析,包括直方图分析,相邻像素相关性分析,信息熵分析,密钥敏感性分析,密钥空间分析以及差分攻击分析等.数值实验表明该算法是一种有效的图像加密算法,在图像信息安全方面具有一定的应用价值.

A chaos-based image encryption scheme with permutation-diffusion architecture is proposed. In the permutation process, the 8-bit gray scale image with size is expanded to a 4-bit gray scale one with size by dividing the plain-image into two parts： one consisting of the higher 4 bits and one consisting of the lower 4 bits. The resulted 4-bit gray scale image is then set to be blocks with size and shuffle the image at block level. To achieve more avalanche effect and larger key space, a chaotic Bernoulli shift map based bilateral diffusion function is applied as well. The security and performance of the proposed image encryption have been analyzed, including histograms, correlation coefficients, information entropy, key sensitivity analysis, key space analysis, differential analysis, encryption rate analysis, etc. All the experimental results suggest that the proposed image encryption scheme is robust and secure.