一种简单的二维映射及其图像加密算法

为了实现图像安全、快速加密,利用单边拉伸的思想设计了一种图像加密算法.映射由左映射和右映射两个子映射组成,通过对图像的拉伸和折叠处理,实现图像的混沌加密.首先从左至右(或从右至左)方向,依次将方图的列像素插入到行像素之间,将像素依次连接,原图像被拉伸成一条直线.然后,按照原图像大小,将直线折叠成为一个新的图像.该过程是可逆的,能应用于图像加密.本文推导了映射的数学表达式,设计了一种图像加密算法,将密钥设计为左映射和右映射的迭代次数.加密算法具有加密速度快、安全性高、没有信息损失、可移植性强、容易软、硬件实现等特点,是一种新的安全、有效的加密算法.

Image encryption based on a simple two-dimensional chaotic mapping

In order to satisfy the need of security and speed of image encryption,this paper proposes a simple two-dimensional chaotic mapping which can be used in image encryption.It consists of left mapping and right mapping,and can encrypt images by processing image stretch-and-fold.For left mapping,firstly,each pixel of the first column of a square image was inserted into adjacent two pixels of the first row one by one.Then the second column was inserted into adjacent two pixels of the second row.By repeating the process for the rest of the image,the image was stretched to a line of pixels.Finally the line was fold over to a new square image which size is the same as the plain image.The right map is symmetric to the left mapping.The two-dimensional mapping shuffles the positions of image pixels which are invertible.This paper formulates the algorithm of the mapping,designs a method of key generation and analyses the security of the proposed image encryption.The simulation shows that the image encryption has rapid speeds,high security,no message loss and it is suitable for hardware/software realization.