基于混沌系统的对称图像加密方案

采用基于外部密钥的复合混沌系统对数字图像进行对称加密，由外部密钥产生混沌系统的初始值。复合混沌系统由2个Logistic系统构成，一个用来产生置换矩阵，对图像进行像素置换操作，另一个用来产生灰度扰乱序列。在对灰度扰乱过程中，使用基于外部密钥导出的子密钥对灰度扰乱序列进行采样。在置换过程中，通过加入置换矩阵信息，使位置置换和像素替代过程以简单有效的方式复合，提高系统的耦合性。

Symmetric Image Encryption Scheme Based on Chaotic System

This paper presents a new image encryption scheme based on composite chaotic system. An external key and two logistic systems are employed for encryption, which shuffle positions and substitute grey values of pixels of image. In the process of grey value substituting, it adopts sub key induced by external key to take samples. Through adding information of shuffle position matrix into the process of grey value substituting, processes of shuffle positions and substitute grey values are mixed in a simple and effective way, which improves coupling property of the encryption system.