基于广义猫映射的一种图像加密系统

An image cryptosystem based on general cat map

本文首先将猫映射推广为广义猫映射,然后将图像的像素坐标和灰度作为广义猫映射的初始值,映射参数和迭代次数作为密钥,对图像进行加密。本加密方案具有置换、替代、扩散等加密系统的基本要素,能抗明文攻击和选择明文攻击,密钥长度可变,密钥空间巨大,密文和明文大小可变且相同,计算时间也较短,可用于图像和数据块加密后传输。

In this paper we first extend the cat map to 揼eneral cat map? then, taking the pixel抯 location and gray level as the initial condition, and the parameters and iteration number as the keys, we apply the general cat map to encrypt the image. Our system contains permutation, substitution and diffusion, which are necessary factors for a good cryptosystem. It is resistive to known plain-text type of attack and chosen plain-text type of attack. It抯 advantages include variable key length and variable image (data block) size, very huge key set, cipher-text with the same size as plain-text, both fast encryption and decryption process.