摘要
对一种典型的置乱和替代结构图像混沌加密算法进行了安全性分析,运用选择明文攻击方法成功破解了该算法中位置置乱和像素值替代变换的等效密钥,并能利用破解的等效密钥解密出目标明文.基于此,提出了一种基于混沌的改进型置换-替代结构图像加密算法.在改进算法的像素位置变换过程中,随机选择两个不同区域内的像素对进行位置交换,明显提高了像素的置乱度.在改进算法的像素值变换过程中,将像素值变换的扩散矢量与像素位置变换的置乱矢量相耦合,有效地提高了密钥矢量的破解难度.理论分析和实验结果表明,改进算法不仅增强了抵抗选择明(密)文攻击的能力,而且改善了密文随机性和敏感性等多项密码学性能.
This paper analyzes the security of a typical chaotic image encryption algorithm based on permutation substitution procedure. By applying chosen plaintext attack, we demonstrate that a hacker can determine the permutation vector and the whole key sequence used respectively in permutation and diffusion procedure, which can be exploited to reveal the plain image. Then we proposed an improved permutation-substitution image encryption algorithm based on chaos. In the pixel positions permutirg procedure of the proposed algorithm, we select randomly pixel pair between two different regions and exchange their positions to increase scramble degree of pixels. In the pixel values substituted procedure of the proposed algorithm, the diffusion vector of substituting procedure is coupled with permu- tation vector of permuting procedure to enhance the difficulty of cracking the secret key vectors. The theoretical analysis and experimental results show that the improved algorithm has not only enhanced the capabilities in resisting against chosen plaintext and chosen ciphertext a：tacks, but also improved the cryptographic performances in randomness, sensitivity, and so on.
出处
《武汉大学学报（理学版）》
CAS
CSCD
北大核心
2014年第5期447-452,共6页
Journal of Wuhan University:Natural Science Edition
基金
国家自然科学基金资助项目(61073187)
湖南省教育厅科研项目(13C995)
广西教育厅重点科研项目(201202ZD080)
关键词
图像加密
混沌系统
密码分析
选择明文攻击
image encryption
chaotic system
cryptanalysis
chosen plaintext attack
