Research And Implementation Of Visually Meaningful Image Encryption Algorithm

The 21st century is an era of information,and all kinds of convenient living welfare bathe the ordinary people in all walks of life.However,people are also suffering from all kinds of troubles caused by information leakage.Therefore,the protection of some confidential information has always been the focus of people's attention,such as image encryption technology.For traditional image encryption,people encrypt plaintext images into noise-like or textured images.The security of this process depends on the encryption algorithm designed for it.However,the problem is that this kind of noise-like image is equivalent to passing a signal of “the image has been encrypted” to the attacker,and it is inevitable to suffer various attacks.To solve this problem,this paper carries out in-depth research on the visually meaningful image encryption algorithm(VMIE algorithm for short).In this kind of scheme,the encrypted image is presented as an image with no visual difference from the ordinary image,which can avoid the attention of the attacker.The innovative results achieved include:Firstly,a visually meaningful image encryption algorithm based on carrier modification is designed.The whole algorithm is divided into three parts.The first part of the algorithm is to generate fractional-order Qi hyperchaotic sequences and use the initial value of the chaotic system as the key.In the second part,the fractional-order Qi hyperchaotic sequence is used to pre-encrypt the image.Similar to the traditional image encryption algorithm,this part converts the plaintext image into noise-like image by scrambling and diffusing the plaintext image.Moreover,we prove the security of the algorithm from image histogram,correlation and other aspects.The third part is the second step encryption algorithm.In this part,an ordinary image is selected as the carrier,and the pre-encrypted image obtained in the second part is embedded in it through some mathematical models.The final encrypted image is almost identical to the cover image.Because the cover image is modified to a certain extent,it is called VMIE algorithm based on carrier modification.We also analyze the security and robustness of the encryption algorithm.Experimental results show that the VMIE scheme has excellent performance of image encryption.Secondly,a coverless VMIE algorithm is proposed.The first part of the algorithm is to generate random sequences by quantum random walk system and use the initial value of quantum random walk system as the key.In the second part,a two-particle quantum random walk system on a n node ring is applied to pre-encrypt the image.Similarly,the plaintext image is transformed into noise-like image by scrambling and diffusing the image.Moreover,we prove the security of the algorithm from image histogram,correlation and other aspects.The third part is the second step encryption algorithm.This part hides pre-encrypted image data by synthesizing fingerprint image.Because the coverless steganography technology is adopted,that is,the cover image is not modified to hide the data,so it is called the coverless VMIE algorithm.The encrypted images obtained by the algorithm are presented as a set of fingerprint images,which are not only indistinguishable to human eyes,but also can avoid the machine's steganalysis.We also analyze the security and robustness of the encryption algorithm.The experimental results show that the VMIE scheme is effective and safe.Finally,a visually meaningful image encryption system is designed and implemented based on the above research results.The system is not only simple interface,but also simple operation.Firstly,the system can easily realize the operation of image encryption and decryption.At the same time,various analysis on encryption effect can be carried out.Next,the system can demonstrate chaotic systems and quantum random walk systems.It is worth mentioning that the system can also simulate various attacks in the process of image transmission and try to decrypt the image.