A novel image multi-encryption architecture based on hybrid keystream sequence generated by a single hyperchaotic system and Haar discrete wavelet transform (HDWT) is proposed. The architecture consists of a pre-cipher stage, first encryption operation, Haar discrete wavelet decomposition stage and a second encryption operation. In the pre-cipher stage, the algorithm applies two-level pixel position permutation of the image. The first encryption operation is accomplished by diffusing the pixel's numbers with keystream sequence generated by a sequence generator SG-1. The resulting cipher image is decomposed using two-dimensional HDWT decomposition technique. The decomposed image is further encrypted through operation between keystream sequence generated by sequence generator SG-2 and bytes of the decomposed image which are selected with the aid of a novel pseudo – 4 bit Boolean truth table-based byte selection mechanism. SG-1 and SG-2 are special cases of the hyperchaotic system and are evolved online by separately nullifying selected parameters of the hyperchaotic system. The novelty of the proposed architecture lies in the possibility of increasing the number of sequence generators, which can result in exponentially huge key space and fast encryption speed. A comprehensive complexity analysis of performance, security and robustness to attacks, confirmed the feasibility of the architecture.

中文翻译：

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基于混合密钥流序列和Haar离散小波变换的图像多重加密体系结构

提出了一种基于单个超混沌系统生成的混合密钥流序列和Haar离散小波变换（HDWT）的图像多重加密体系。该体系结构包括预加密阶段，第一加密操作，Haar离散小波分解阶段和第二加密操作。在预加密阶段，该算法应用图像的两级像素位置置换。通过将像素的数字与由序列发生器SG-1生成的密钥流序列进行扩散来完成第一加密操作。使用二维HDWT分解技术分解生成的密码图像。通过序列生成器SG-2生成的密钥流序列与分解图像的字节之间的操作，可以对分解后的图像进行进一步加密，借助新的基于伪4位布尔真值表的字节选择机制选择分解后的图像的字节。SG-1和SG-2是超混沌系统的特例，它们是通过分别使超混沌系统的选定参数无效而在线发展的。所提出的体系结构的新颖之处在于可能增加序列发生器的数量，这可能导致成倍增加的密钥空间和快速的加密速度。对攻击的性能，安全性和鲁棒性进行的全面复杂性分析证实了该架构的可行性。SG-1和SG-2是超混沌系统的特例，它们是通过分别使超混沌系统的选定参数无效而在线发展的。所提出的体系结构的新颖之处在于可能增加序列发生器的数量，这可能导致成倍增加的密钥空间和快速的加密速度。对攻击的性能，安全性和鲁棒性进行的全面复杂性分析证实了该架构的可行性。SG-1和SG-2是超混沌系统的特例，它们是通过分别使超混沌系统的选定参数无效而在线发展的。所提出的体系结构的新颖之处在于可能增加序列发生器的数量，这可能导致成倍增加的密钥空间和快速的加密速度。对攻击的性能，安全性和鲁棒性进行的全面复杂性分析证实了该架构的可行性。