一种对角线拉伸的混沌映射图像加密算法

利用双边对角线拉伸的思想,提出一种利用图像加密的可逆二维混沌映射.该映射由左映射和右映射2个子映射组成,通过对图像的拉伸和折叠处理,实现图像的混沌加密.左映射的过程为:首先利用图像性质,从左至右将每列的像素逐个插入到对应的每行像素之间;重复这样的过程,原始图像拉伸成为一条直线;最后,按照原始图像的大小,将这条直线折叠成为一个新的图像.右映射的方向是从左至右.映射置乱了像素的位置,过程是可逆的.推导出了映射的数学表达式,设计了密钥产生的方法,分析了图像加密算法的安全性问题,仿真验证了该图像加密算法的有效性.

An image encryption approach based on a chaotic map by diagonal stretch

Based on bilateral diagonal stretch,this paper proposes a new invertible two-dimensional map which can be used in image encryption. The map consists of the left map and the right map, which can encrypt images by processing image stretch-and-fold. The process of the left map is that a square image is stretched respectively by diagonal firstly. Pixels of each column can be inserted into pixels of each horizon. Then, the original image can be stretched to a line. Finally the line is fold over to a new square image whose size is same as the original image. The right map is from right to left. The left map and the right map shuffle the positions of image pixels which are invertible. This paper formulates the algorithm of the map,designs a method of key generation and analyses the security of the proposed image encryption. The simulation results show that the proposed encryption approach is valid.