【摘要】 为了提高基于混沌系统的图像加密算法的安全性，通过耦合两个已有的四维子系统，得到一个新的广义哈密顿混沌系统。该系统满足哈密顿能量保守和相空间体积保守，而且呈现出多混沌流共存的动态性能。对该广义哈密顿混沌系统进行美国国家标准与技术研究院(NIST)测试，发现其具有良好的伪随机性，适用于图像加密。结合二维离散小波变换，提出一种基于该广义哈密顿混沌系统的图像加密算法。该算法利用广义哈密顿混沌系统作为伪随机信号发生器，以此提高算法的安全性，避免重构吸引子的攻击；利用二维离散小波变换，通过打乱图像的低频部分，提高加密算法的运行速度。仿真研究表明，该图像加密算法具有很好的加密效果。安全分析结果进一步表明，该加密算法适合用于图像加密应用。更多还原

【Abstract】 To improve the security of image encryption algorithms based on chaotic systems,a new generalized Hamiltonian chaotic system is obtained by coupling two existing four-dimensional subsystems. The system not only satisfies Hamiltonian energy conservation and phase space volume conservation,but also presents the dynamic performance of coexistence of multiple chaotic flows. The generalized Hamiltonian chaotic system is tested by National Institute of Standards and Technology(NIST)and found to have good pseudo-randomness,which is suitable for image encryption. An image encryption algorithm based on this generalized Hamiltonian chaotic system is proposed by combining the two-dimensional discrete wavelet transform. The algorithm employs the generalized Hamiltonian chaotic system as a pseudo-random signal generator as a way to improve the security of the algorithm and avoid the attack of the reconstructed attractor;and utilizes the twodimensional discrete wavelet transform to improve the running speed of the encryption algorithm by disrupting the lowfrequency part of the image. Simulation studies show that this image encryption algorithm has good encryption results. The security analysis results further show that the encryption algorithm is suitable for image encryption applications.更多还原