利用图像分割思想的二维混沌映射及图像加密算法

根据二维混沌映射思想,设计了一种新的图像加密算法。二维混沌映射包括左映射和右映射两个子映射。通过对图像的拉伸和折叠处理,实现图像的混沌加密。沿图像的对角线方向,将方图分割为上下两个等腰三角形图像;利用等腰三角形图像两列像素之间的像素数目差,以水平方向,依次将某列中的像素插入到相邻下一列像素之中,直至将原始图像拉伸成为一条直线。最后,按照原始图像大小,将这条直线折叠成一个新的图像。映射是可逆的,可应用于图像加密,密钥设计为二维混沌映射的左映射和右映射的组合。进行了仿真研究,结果表明:当密钥为64 bit时,密钥空间为1.84×10¹⁹,加密速度约为3 Mb/s。该加密算法具有加密速度快、安全性高、没有信息损失、可移植性强和容易软、硬件实现等特点。

Novel 2D chaotic map based on image segmentation and image encryption approach

A novel image encryption approach based on a new 2D chaotic map and consisting of left map and right map utilizing image segmentation was proposed. The chaotic encryption of image is realized by processing image stretch-and-fold. Firstly, a square image was divided into two isosceles triangles along the diagonal, utilizing the difference of the pixel numbers of two adjacent columns of the triangles, each pixel in a column was inserted to the next adjacent column. Then, the original image could be stretched to a line. Finally, the line was folded over to a new square image whose size was the same as the original image. The process was invertible,so that the positions of image pixels could be used in image encryption. Taking the numbers of the left map and the right map as the keys, the algorithm of the map was formulated, the method of key generation was designed and the security of the proposed image encryption was analyzed. The simulation results show that the proposed encryption approach is valid. When the key is 64 bits, the whole key space size is 1.84×10¹⁹ and the speed of encryption is 3 Mb/s. The image encryption has several advantages such as rapid speeds, high security and without message loss and it is easy for hardware/software realization.