摘要： 分析了一个基于混沌序列的图像加密算法的安全性，发现该加密算法本质上是一个移位密码且密钥空间太小，利用古典密码中对移位密码的分析方法得到混沌序列，进而给出了穷举参数求解其密钥的已知明文攻击方法。对于大小为M×N的明文图像，该攻击方法的计算复杂性为O(M+N)。理论分析和实验结果均表明该图像加密算法是不安全的。

关键词: 混沌密码, 图像加密, 密码分析, 已知明文攻击

Abstract: The security of a chaos sequence-based image encryption and decryption algorithm is analyzed. The encryption algorithm is a shift cipher essentially and its key space is too small. The chaotic sequence is obtained by using the analysis method of shift cipher of classical cipher. A known plaintexts attack is proposed by exhaustive parameter search. For a M×N plain image, the computing complexity is O(M+N). From the analysis in theory and experimental results, this image encryption algorithm is proved insecure.

Key words: chaotic cipher, image encryption, cryptanalysis, known plaintexts attack

中图分类号: 

• TN918