Abstract: According to the principle of chosen plaintext attack, a novel hyperchaotic image encryption scheme is analysed, and the results show that the image encryption scheme can not resist against chosen plaintext attack. An improved algorithm is proposed based on hyperchaos and the performance analysis as well as experimental tests are performed. The theoretical analysis and experimental results indicate that the improved algorithm can overcome these flaws and has better cryptographic performances in statistical characteristics, difference characteristics and speed of encryption.

Key words: hyperchaos, image encryption, chosen plaintext attack, cryptanalysis

摘要： 根据选择明文攻击原理，对一种超混沌图像加密算法进行了分析，结果表明该算法不能抵抗选择明文攻击。提出了一种改进的超混沌图像加密算法；对改进算法进行了安全性分析和实验测试。理论分析及实验结果表明，改进算法克服了原算法不能抵御选择明文攻击的缺陷，而且能拥有更好的统计特性、差分特性等密码学特性和更高的加密速度。

关键词: 超混沌, 图像加密, 选择明文攻击, 密码分析