Abstract: A new image encryption algorithm based on combined high-dimension chaotic system is presented.Firstly，it uses the generalized cat mapping to diffuse the image，then it uses the Lorenz system to confuse the diffused image.The results demonstrate that the algorithm has good properties of confusion and diffusion.The key space is large enough to resist the brute-force attack.For the encrypted image the distribution of pixel-values has a random-like behavior and the values of adjacent pixels satisfy zero correlation，showing that the proposed scheme is of relatively high security.

Key words: Chaotic, image encryption, generalized cat mapping, Lorenz, confusion, diffusion

摘要： 提出了一种基于高维混沌系统组合的图像加密算法。该算法首先利用广义猫映射对图像进行置乱，然后利用Lorenz系统对置乱后的图像进行替代变换。研究结果表明，该算法具有良好的像素值混淆、扩散性能和较大抵抗强力攻击的密钥空间，加密图像像素值具有类随机均匀分布特性，且相邻像素的值具有零相关特性。这些结果表明所提出的方案具有较高安全性。

关键词: 混沌, 图像加密, 广义猫映射, Lorenz, 替代, 置乱