一种基于混沌的代换-置换结构图像加密算法  

Substitution-Permutation Network Structured Image Encryption Algorithm Based on Chaotic Map

作　　者：蔡俊[1] 陈昕[1] 向旭东[2] 

机构地区：[1]北京信息科技大学计算机学院,北京100101 [2]北京科技大学计算机与通信工程学院,北京100083

出　　处：《计算机科学》2014年第9期158-164,共7页Computer Science

基　　金：国家自然科学基金面上项目(61370065)资助

摘　　要：近年来,随着多媒体技术的发展,互联网上数字图像相关内容和应用的比例越来越高,其安全性也日益受到人们的关注。图像的安全性,一般通过加密方法来保证。图像加密算法中,基于置乱-扩散结构的加密算法因其充分考虑图像数据二维分布的特点,特别适合图像数据的加密。然而,该加密算法存在安全性不高、扩散效率低,以及密钥扩展计算复杂度高等问题。通过引入分组密码学中的代换-置换(SP,Substitution-Permutation)结构,提出了一种基于混沌的SP结构图像加密算法SPCME,该算法采取3种策略:(1)通过混沌映射进行置换和扩散,采用AES算法的S盒进行字节代换,以增强算法安全性;(2)使用双向的置乱-扩散策略,加快扩散速度;(3)运用简单的异或和移位操作,提高密钥扩展效率。为评价该算法的性能,文中做了密钥空间分析、密钥敏感性分析、统计直方图分析、相邻像素相关性分析、信息熵分析、差分攻击分析等大量的性能分析实验。实验结果表明,该算法仅通过3轮迭代就可达到与以前提出的图像加密算法相同的安全级别,加密效率明显提高。Various image encryption algorithms based on the permutation-diffusion structure have been proposed in the past few years. However, permutation and diffusion are considered as two separate stages,making image encryption vulnerable to attacks. Moreover, the algorithms, in general, have low diffusion efficiency and high computational complexity in key scheming. To solve these problems, this paper proposed a SP（Substitution-Permutation） network image encryption algorithm based on chaotic map. The proposed algorithm adopts the following three strategies. （1） To further en hance the security of the cryptosystem, XOR and S-box operations are introduced in the beginning of each encryption round; （2） An bidirectional permutation-diffusion strategy is proposed to accelerate the spreading process; （3） Simple circular bit shift and XOR operations are used to improve the efficiency of key scheming. We conducted a rich set of cryptanalyses on the proposed algorithm, e. g. , key space analysis, key sensitivity analysis, various statistical analyses and differential analysis. Analytical results demonstrate that the proposed algorithm reaches the same security level of previously proposed counterparts in merely three iterations with high efficiency, and is thus applicable for secure image encryption.

关 键 词：SP结构 图像加密 混沌 三维Arnold映射 LOGISTIC映射 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构]