一种基于二维可逆映射的图像加密算法

提出了二维可逆映射在图像加密中的应用.可以通过置乱图像像素位置实现图像加密.二维可逆映射可以高效地实现图像像素置乱.二维可逆映射由压缩拉伸和折叠两个子映射组成.压缩拉伸映射,使原始图像变换成线,折叠映射使线变换成图.所有可逆映射构成了可逆映射集合.经过扩散处理改变像素值,实现图像加密.二维可逆映射的引入扩大了密钥空间,并增强了对密钥变化的敏感度.新的加密方法提高了加密图像的安全性且加快了加密速度.仿真验证了二维可逆映射图像加密算法的有效性.

An Image Encryption Approach Based on a Two-dimensional Reversible Map

An invertible two-dimensional map is applied to the image encryption. Shuffling the positions of image pixels can realize the image encryption. The invertible two-dimensional map can realize the shuffling of the pixels positions. The map consists of a stretch map and a fold map. The stretch operation transforms the original image into a line and the fold operation transforms the line into an image which has the same size as the original one. All maps construct the map set. After the diffusion, the pixel values are changed, then the image is encrypted. The application of the invertible two-dimensional map enlarges the key space of the encryption and enhances the sensitivity to the key changes. The new approach improves the security and shortens the encryption time. The simulation results show that the proposed encryption approach is valid.