对一类超混沌图像加密算法的密码分析与改进

对一种超混沌图像加密算法及其改进版进行了安全性分析, 结果表明该类算法的置乱过程都是与混淆过程相脱离的, 且混淆过程的加密公式简单; 因此都不能抵抗选择明文和选择密文攻击. 进而提出了一种改进的加强型超混沌图像加密算法; 改进算法包含两轮像素值替代加密操作, 并使得密文与明文、密钥之间的关系更复杂. 安全性分析和实验测试表明, 改进算法不仅克服了原算法不能抵御选择明文和选择密文攻击的缺陷; 而且具有时间开销更小和抗差分攻击性能更好的优势.

Cryptanalysis and improvement of a class of hyperchaos based image encryption algorithms

The security of a class of hyperchaotic image encryption algorithms is analysed. The results show that the shuffling process can be separated from the confusion process, and the formulas of encryption are simple, which makes the ciphertext cannot resist the attacks from chosen plaintext and ciphertext. Then we propose an improved and enhanced algorithm based on hyperchaos. The improved algorithm includes two rounds of encryption operation. The theoretical analyses and the experimental results indicate that the improved algorithm can overcome these flaws and has better cryptographic performances in resisting differential attacks and speed of encryption.