一种新的可逆二维混沌映射图像加密算法

Image encryption approach based on a new invertible two-dimensional map

提出了一种用于图像加密的可逆二维混沌映射,该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,实现了图像的混沌加密。首先沿图像的对角线方向将正方形图分为上下两个部分并重新组合成一个平行四边形的图像;然后利用平行四边形图像的两列像素之间的像素数目差将某列中的像素插入到相邻下一列像素之间。经过这样的过程,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。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。

A new invertible two-dimensional map which can be used in image encryption is proposed. The map consists of the left map and the right map. It can encrypt images by processing image stretch-and-fold. Firstly a square image is divided in- to two parts by diagonal and a parallelogram is reformed. Utilizing the difference of the pixel numbers of two adjacent columns of the parallelogram image, each pixel in a column is inserted to the adjacent column. Then, the original image can be stretched to a line. Finally the line is fold over to a new square image which size is same as the original image. The algorithm of the map is formlated, a method of key generation is designed and the security of the proposed image encryption is analyzed. The simula- tion results show that the proposed encryption approach is valid.