【作者】 王丹；

【导师】 刘立东；

【作者基本信息】 长安大学 ， 信息与通信工程， 2021， 硕士

【摘要】 随着网络的飞速发展,大量的图像通过公共网络传输,然而,利用网络开放性和共享性的特点来截取有用信息的恶意行为,严重损害了通信各方的利益,因此,保证图像的数据安全性以及外观安全性至关重要。混沌系统具有对初始值的极度敏感性、遍历性、以及伪随机性,非常适用于对图像进行加密。DNA计算技术具有并行性高、存储量大、功耗低的特点,许多学者将DNA计算和混沌进行了结合设计出更加高效和安全的加密算法,使得算法的加密性能更加出色。为了保证图像的数据安全性以及外观安全性,本文给出了基于超混沌和DNA计算编码的与明文相关的加密算法,主要内容如下:(1)本文给出了基于超混沌和动态DNA编码的图像加密算法,在加密过程中,像素级的扩散和置乱过程以及DNA动态编码规则均与明文关联。首先对明文图像进行像素级的扩散重写,然后对扩散图像的像素值进行求和;其次,像素级的置乱规则是由像素和以及外部密钥生成的,因此两幅具有一比特差值的明文图像将得到完全不同的置乱规则;第三,选取像素级置乱后图像的一部分像素值和外部密钥生成用于DNA级扩散过程的密钥流,扩散过程采用DNA动态编码和解码;最后,执行二次置乱操作来得到密文图像。(2)本文给出了基于超混沌和DNA编码的视觉意义图像加密算法,预加密阶段中的算法对明文敏感,扩散操作采用DNA动态编码规则,能够充分利用DNA编码的多样性,隐藏阶段中使用配对函数可逆隐藏明文像素和,避免了加密每幅明文图像均需传输密钥等问题,将载体图像进行置乱后再隐藏信息增加了算法的安全性。首先,利用6D超混沌系统以及明文图像的像素和生成置乱矩阵以及DNA动态编码解码矩阵完成预加密阶段;然后在隐藏阶段中,采用二代整数小波变换将载体图像转换为四个矩阵,将预加密阶段的密文图像以及密钥值嵌入到三个细节子带矩阵中,完成密文和密钥值的双重隐藏;最后对隐藏后的图像进行逆整数小波变换得到视觉意义的加密图像。更多还原

【Abstract】 With the rapid development of the network,lots of images are spread over the public network.However,the malicious behavior of intercepting useful information by the openness and sharing in network,which seriously damages the interests of all communication parties.Therefore,it is very important to ensure the data security and appearance security of images.Chaotic systems have many features such as the property of pseudo-random,sensitivity to the initial values and parameters,ergodicity,and high complex behavior,which can be well employed in image encryption.DNA molecule has characteristics of the massive parallelism,superior information storage capabilities and ultra-low energy consumption,Many scholars combine DNA computing and chaos to design a more efficient and secure encryption scheme,which makes the encryption performance of the scheme better.To ensure the data security and appearance security of images,this thesis studies a plaintext-related image encryption scheme based on hyper chaotic system and DNA encoding.The main work of this thesis are as follows:(1)This thesis presents an image encryption scheme combining the hyperchaos and dynamic DNA encoding.In the encryption process,pixel-level diffusion,pixel-level permutation and dynamic DNA encoding rules are related to the plaintext image.Firstly,the pixel values of plaintext image is rewritten,and then the pixel values of the diffused image are summed.Secondly,the pixel-level permutation rules are obtained by the plaintext image and external secret key.Therefore,the permutation rules are different when the plaintext images with one bit difference.Thirdly,In the DNA-level diffusion process,this thesis selects a part of pixel values of the pixel-level permutated image and external secret key to generate key streams used in DNA-level diffusion process.Finally,the second permutation operation is performed to get the cipher image.(2)This thesis presents a visually meaningful image encryption scheme combining the hyperchaos and dynamic DNA encoding.In the pre-encryption phase,the scheme is sensitive to the plaintext,and the diffusion operation is based on DNA dynamic encoding rules,which can take advantage of the diversity of DNA codes.In the embedding stage,the sum of the plaintext image is embedded into the carrier image reversibly by the pairing function,which avoids the problem that every plaintext image all needs to transmit secret keys.The security of the scheme is enhanced by permutating the carrier image before hiding the information.Firstly,6D hyper chaotic system and pixel sum of plaintext image are used to generate the permutation matrix and the DNA dynamic encoding and decoding matrix to complete the pre-encryption phase.Then,in the hiding stage,the carrier image is transformed into four matrices by using the second generation integer wavelet transform,and the ciphertext image and the key values in the pre-encryption stage are embedded into three detail subband matrices to complete the double hiding process.Finally,the visual meaning encrypted image is obtained by the inverse integer wavelet transform.更多还原