Abstract: A new image encryption theme based on dual chaotic systems is proposed. Three-dimensional secret key sequences are generated by combining Chen’s system with Logistic map, and the new encryption sequences are obtained from the three-dimensional secret key sequences by sampling. Then image scrambling algorithm and encryption algorithm are proposed, scrambling algorithm shuffle the positions of the image pixels by using one-dimensional Logistic chaotic sequence, encryption algorithm uses packet encryption and the double encryption to encrypt the value of the pixel. The experimental and theoretical results demonstrate that the algorithm has well properties of confusion and diffusion. The algorithm has strong ability against statistical attacks and enough key space. For the encrypted image the distribution of grey values has a random-like behavior and the adjacent pixels satisfy zero correlation. These results show that the proposed scheme has high security.

Key words: image encryption, Chen’s system, Logistic map, double encryption

摘要： 提出了一种新的基于双混沌系统的图像加密方案。把Chen’s系统和Logistic映射结合起来产生随机性更加良好的三维混沌密钥序列，并从密钥序列中通过采样提取出新的用于加密的序列。提出了图像置乱算法和替代加密算法，利用Logistic映射产生的一维混沌序列来实现像素位置的置乱，像素值加密算法采用按分组进行加密和二次加密来对像素值进行加密。通过实验测试表明：算法具有良好的像素值混淆和扩散性能，有较强的抗统计攻击的能力和足够大的密钥空间，加密图像像素值具有类随机均匀分布特性，且相邻像素具有零相关特性。这些结果表明了所提出方案有很高的安全性。

关键词: 图像加密, Chen’s系统, Logistic映射, 二次加密