Abstract: To solve the shortcoming of encryption efficiency and security of some existing image encryption algorithms, this paper proposes a new image encryption algorithm. Firstly the image is rearranged by using Kent mapping, and then the location of the image is scrambled. The Logistic mapping is used to construct the subscript sequence, and the subscript sequence is used to XOR the pixel of the scrambled image. Finally, the XOR value is replaced with the generalized Gray code. Experiments show that the algorithm is encrypted with the following features：large enough key space, evenly distributed gray histogram, weak correlation of pixels and so on. The proposed algorithm has good security and encryption effect.

Key words: chaotic mapping, image encryption, position scrambling, pixel replacement, generalized Gray code

摘要： 针对部分现有图像加密算法加密效率与安全性的不足，提出了一种新的图像加密算法。算法利用Kent映射对图像进行分块重排列，然后再重新进行全局位置置乱。接下来利用Logistic映射构造下标序列，利用下标序列对置乱图像的像素点进行异或。最后将异或后的像素值进行广义Gray码变换。实验表明，该算法加密后的图像满足如下特点：足够大的密钥空间、均匀分布的灰度直方图、弱相关性等。该算法具有良好的安全性和加密效果。

关键词: 混沌映射, 图像加密, 位置置乱, 像素替换, 广义Gray码