一种基于压缩感知和多维混沌系统的多过程图像加密方案

Multi-process image encryption scheme based on compressed sensing and multi-dimensional chaotic system

随着计算机科学的快速发展,信息的存储和传播常常在各类计算机硬件以及多种网络之间进行,传统的信息加密方案已逐渐不再适用.因此,基于计算机的信息加密算法近年来逐步成为研究热点.通过结合小波包变换、压缩感知、混沌系统等理论,一种基于压缩感知和多维混沌系统的多过程图像加密方案被提出.该加密方案实现了针对灰度图像的压缩和加密及对应的解压、解密过程.小波包变换理论被应用到图像的预处理阶段对原始图像进行小波包分解,同时结合阈值处理方法对分解后所得的图像信号分量进行分类,并在之后的处理过程中根据图像信号分量的特性对其有区分地进行压缩、加密或者保留.在图像压缩阶段,引入压缩感知算法克服传统采样定理采样成本高及重构质量偏低等弊端.在图像加密阶段,结合多类、多维度混沌系统对相关图像信号分量进行置乱.最后,应用压缩、加密以及小波包变换的逆过程实现对原始图像的完整重构.仿真结果表明,该图像加密方案在抵抗外界干扰时凭借算法鲁棒性有效地保护了密文图像的基本信息,且在应对明文攻击等破解手段时不泄露任何有用信息.此外,经该加密方案加密后的密文图像的信息熵及相关系数等指标相比于参考文献中加密算法更加接近于理想值,其加密性能有明显的提升.

With the rapid development of computer science, the storage and dissemination of information are often carried out between various types of computer hardwares and various networks. The traditional information encryption scheme has gradually disappeared. Therefore, computer-based information encryption algorithms have gradually become a research hotspot in recent years. By combining the theory of wavelet packet transform, compressed sensing and chaotic system, a multi-process image encryption scheme based on compressed sensing and multi-dimensional chaotic system is proposed. The encryption scheme implements compression and encryption for grayscale images and corresponding decompression and decryption process. The wavelet packet transform theory is applied to the image preprocessing stage to perform wavelet packet decomposition on the original image. At the same time, the image signal components obtained by the decomposition are classified according to the threshold processing method, and the characteristics of the image signal components are processed in the subsequent processing. They are compressed, encrypted, or reserved in a differentiated manner. In the image compression stage, by introducing the compressed sensing algorithm to overcome the shortcomings of the traditional Nyquist sampling theorem, such as high sampling cost and low reconstruction quality, the compression efficiency and compression quality are improved while the ciphertext image reconstruction quality is guaranteed. In the image encryption stage, the encryption scheme combines multi-class and multi-dimensional chaotic systems to confuse and scramble the related image signal components,and introduces a high-dimensional chaotic system to make the encryption scheme have a large enough key space to further enhance the ciphertext image reliability. Finally, the complete reconstruction of the original image is achieved by applying the inverse of compression, encryption and wavelet packet transform. The simulation results show that the image encryption scheme effectively protects the basic information about ciphertext images by virtue of algorithm robustness against external interference, and does not reveal any useful information when dealing with cracking methods such as plaintext attacks. In addition, the information entropy and correlation coefficient of ciphertext images encrypted by this encryption scheme are closer to ideal values than those of the encryption algorithm in the references, and its encryption performance is significantly improved.