Research On Image Encryption Algorithm Based On Hyper Chaotic System And DNA Encoding

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.