一种基于复合混沌序列的图像加密算法安全分析

针对一种基于复合混沌序列的图像加密算法进行了安全分析,该加密算法采用置换—正向扩散—逆向扩散三级加密,由于正向扩散和逆向扩散采用了相同的一维扩散序列,可将正向扩散和逆向扩散两级加密简化为一级扩散加密,进而将置换—正向扩散—逆向扩散三级加密简化为置换—扩散两级加密;此外,该加密算法生成的混沌序列与明文、密文图像无关,可根据选择明文攻击获取其对应的等效扩散密钥和等效置换密钥.理论分析与数值仿真实验结果表明了该分析方法的有效性;针对原加密算法存在的安全漏洞,提出了若干改进建议以提高其安全性能.

Security analysis of compound chaotic sequence-based image encryption algorithm

This paper analyzed the security of an image encryption algorithm based on compound chaotic sequence, the proposed algorithm adopted three-level encryption structure of permutation-forward diffusion-reverse diffusion. Due to the forward diffusion and the reverse diffusion used the same one-dimensional diffusion sequence, therefore, this paper simplified the two-level encryption structure of the forward diffusion and reverse diffusion to one-level diffusion encryption structure, further, simplified the three-level encryption structure of permutation-forward diffusion-reverse diffusion to two-level encryption structure of permutation and diffusion. Moreover, the chaotic sequences generated by the encryption algorithm were independent of the plaintext images or ciphertext images, consequently, it could crack the corresponding equivalent diffusion keys and equivalent permutation keys by chosen-plaintext attack. Theoretical analysis and numerical simulation experiment results verify the effectiveness of the analytical method. Finally, this paper proposed some improved suggestions for the original encryption algorithm to promote the security.