Wu Xiangjun, Li Yang, Kurths Jürgen
College of Software, Henan University, Kaifeng, China; Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany; Department of Physics, Humboldt University zu Berlin, Berlin, Germany.
College of Software, Henan University, Kaifeng, China.
PLoS One. 2015 Mar 31;10(3):e0119660. doi: 10.1371/journal.pone.0119660. eCollection 2015.
The chaos-based image cryptosystems have been widely investigated in recent years to provide real-time encryption and transmission. In this paper, a novel color image encryption algorithm by using coupled-map lattices (CML) and a fractional-order chaotic system is proposed to enhance the security and robustness of the encryption algorithms with a permutation-diffusion structure. To make the encryption procedure more confusing and complex, an image division-shuffling process is put forward, where the plain-image is first divided into four sub-images, and then the position of the pixels in the whole image is shuffled. In order to generate initial conditions and parameters of two chaotic systems, a 280-bit long external secret key is employed. The key space analysis, various statistical analysis, information entropy analysis, differential analysis and key sensitivity analysis are introduced to test the security of the new image encryption algorithm. The cryptosystem speed is analyzed and tested as well. Experimental results confirm that, in comparison to other image encryption schemes, the new algorithm has higher security and is fast for practical image encryption. Moreover, an extensive tolerance analysis of some common image processing operations such as noise adding, cropping, JPEG compression, rotation, brightening and darkening, has been performed on the proposed image encryption technique. Corresponding results reveal that the proposed image encryption method has good robustness against some image processing operations and geometric attacks.
近年来，基于混沌的图像加密系统得到了广泛研究，以实现实时加密和传输。本文提出了一种利用耦合映射格子（CML）和分数阶混沌系统的新型彩色图像加密算法，以增强具有置换扩散结构的加密算法的安全性和鲁棒性。为了使加密过程更加混乱和复杂，提出了一种图像分割洗牌过程，即先将明文图像分割成四个子图像，然后对整个图像中像素的位置进行洗牌。为了生成两个混沌系统的初始条件和参数，采用了一个280位长的外部密钥。引入密钥空间分析、各种统计分析、信息熵分析、差分分析和密钥敏感性分析来测试新图像加密算法的安全性。同时也对密码系统的速度进行了分析和测试。实验结果表明，与其他图像加密方案相比，新算法具有更高的安全性，并且对于实际图像加密速度较快。此外，对所提出的图像加密技术进行了一些常见图像处理操作的广泛耐受性分析，如添加噪声、裁剪、JPEG压缩、旋转、变亮和变暗。相应结果表明，所提出的图像加密方法对一些图像处理操作和几何攻击具有良好的鲁棒性。
