基于Lorenz混沌系统的数字图像加密算法

鉴于传统图像加密技术和低维混沌加密技术各自的局限性,将Lorenz混沌系统与数字图像置乱技术相结合,设计了一种基于三维混沌系统的数字图像加密算法.首先,对系统输出的实数值混沌序列进行预处理;其次,以此实数值混沌序列直接构造图像置乱索引矩阵;最后,以8×8块为单位实现数字图像的空域加密.分析与仿真结果表明:预处理后的实数值混沌序列具有更强的伪随机特性,更理想的相关特性;三维混沌系统有更大的密钥空间,使算沣法具有很强的抗破译性和抗攻击性;系统三维输出的同时利用,可实现三个或多幅图像的并行加密,提高了算法的加密效率.

Digital Image Encryption Algorithm Based on Three-Dimension Lorenz Chaos System

The Lorenz chaos system was applied to the digital image encryption based on the thought of the higher secrecy of a three-dimension chaos system. Firstly, it carried out pretreatment to a real chaos sequence produced by the system. Secondly, the index matrix of pixel permutation was structured directly by this real chaos sequence. Finally, digital image encryption was realized in the space domain. The results of analysis and simulation show that pretreating the real chaos sequence has the stronger pseudo-random, the better autocorrelation and mutual correlation characteristic. Additionally, the bigger secret-key space of the three-dimension chaos system, the stronger the algorithm can be against decryption attack. Three outputs of the system not only can realize the parallel encryption of three or more images, but also increase the more encryption efficiency of the algorithm.