【作者】 刘芳；

【导师】 孙晶茹；

【作者基本信息】 湖南大学 ， 信息与通信工程， 2020， 硕士

【摘要】 计算鬼成像技术作为一种新兴的光学技术,具备良好的空间分辨能力和抵抗环境干扰的能力,一经出现便引起了研究人员的关注,并广泛用于军事,加密,雷达等领域。随着信息安全技术的发展,计算鬼成像的信息安全问题也引起了人们的重视,如何保证图片信息传输过程中不被窃取及篡改,实现安全的加密通道是计算鬼成像的重要研究课题。因此,研究计算鬼成像技术的安全问题具有重要的现实意义。本文首先概述了课题研究的背景及意义,主要介绍了鬼成像的发展历程以及基于计算鬼成像技术的加密方案国内外研究现状,同时介绍了混沌系统的发展历程以及混沌加密的研究现状。然后,详细论述了鬼成像基本理论、基于计算鬼成像技术加密的流程、压缩感知理论和混沌理论。最后提出了两种基于计算鬼成像技术的加密方案,具体内容如下。(1)本文提出了一种基于超混沌系统和DNA编码的计算鬼成像加密方案。在该方案中,首先利用一个四维的超混沌系统生成四个长的伪随机序列,然后通过DNA操作扩散这些伪随机序列获得相位掩膜序列。最后,由相位掩膜序列生成多个随机相位掩膜矩阵,并加载到空间光调制器(Spatial light modulator,SLM)。激光束通过空间光调制器进行相位调制产生非相干光。经过菲涅耳衍射后,调制光束传输至物平面,透过物体(或反射回来)的光场强度由物平面后方的桶探测器接收,桶探测器探测结果即为密文。仿真结果和安全性分析证明该方案具有良好的性能。(2)本文提出了一种基于KSVD算法的压缩感知鬼成像加密方案。该方案中,首先,用四维超混沌系统生成伪随机序列,通过DNA编码技术对序列进行变换生成相位掩模矩阵从而实现对激光束的相位调制。其次,利用KSVD算法对原始图像进行稀疏表示,将稀疏图像作为待加密图像放置在物平面。然后,调制后的光束照射物平面并由物平面后方的桶探测器接收,图像被加密成一系列的桶探测器探测结果。最后,利用压缩感知重构技术从密文中恢复出原始图像。通过仿真验证和安全性分析表明,所提出的加密方案可有效抵御已知的攻击方法,并在保证解密图像质量的前提下,大大缩减采样次数,提高了图像传输效率。更多还原

【Abstract】 Computational ghost imaging technology,as an emerging optical technology,has good spatial resolution and resistance to environmental interference.Once it appeared,it attracted the attention of researchers and was widely used in military,encryption,radar and other fields.With the development of information security technology,the information security problem of computational ghost imaging has also attracted people’s attention.How to ensure that the image information transmission process is not stolen and tampered,and achieving a secure encrypted channel is an important research topic of computational ghost imaging.Therefore,it is of great practical significance to study the safety of computational ghost imaging technology.This article first outlines the background and significance of the subject research,mainly introduces the development history of ghost imaging and the current research status of encryption schemes based on computational ghost imaging technology at home and abroad,and introduces the development history of chaotic systems and the current research status of chaotic encryption.Then,the basic theory of ghost imaging,the process of encryption based on computational ghost imaging technology,compressed sensing theory and chaos theory are discussed in detail.Finally,two encryption schemes based on computational ghost imaging technology are proposed.The specific contents are as follows.(1)This paper proposes a computational ghost imaging encryption scheme based on hyperchaotic system and DNA encoding.In this scheme,four long pseudo-random sequences are generated by a four-dimensional hyperchaotic system,and then the phase mask sequence is obtained by diffusing these pseudo-random sequences through DNA operations.Finally,multiple random phase mask matrices are generated from the phase mask sequence and loaded into the spatial light modulator(SLM).The laser beam is transmitted through the spatial light modulator,and the spatial light modulator performs phase modulation on the laser beam to generate incoherent light.After Fresnel diffraction,the modulated beam is transmitted to the object plane,and the intensity of the light field transmitted through the object(or reflected back)is received by the barrel detector behind the object plane.The detection result of the barrel detector is the ciphertext.Simulation results and safety analysis prove that the scheme has good performance.(2)This paper proposes a compressed sensing ghost imaging encryption scheme based on KSVD algorithm.In this scheme,first,a four-dimensional hyperchaotic system is used to generate a pseudo-random sequence,and the sequence is transformed by DNA coding technology to generate a phase mask matrix to achieve phase modulation of the laser beam.Secondly,the KSVD algorithm is used to sparsely represent the original image,and the sparse image is placed on the object plane as the image to be encrypted.Then,the modulated beam illuminates the object plane and is received by the barrel detector behind the object plane,and the detection result of the barrel detector is the ciphertext.Finally,the compressed image reconstruction technique is used to recover the original image from the ciphertext.Simulation verification and security analysis show that the proposed encryption scheme can effectively resist known attack methods,and on the premise of ensuring the quality of decrypted images,greatly reduce the number of samples and improve the image transmission efficiency.更多还原