Research Of Image Encryption And Decryption Algorithm Based On Digital Watermarking

As Internet technologies such as artificial intelligence,Internet of things and big data de-veloped rapidly,network security is also facing more challenges.How to portect digital in-formation when transmit or store it has become a hot topic.As the mainstream information carrier,the research on the encryption security of image information becomes particularly important.Therefore,it is of great scientific value to find a security scheme that can effec-tively protect the encrypted image.As another method to protect the image information,digital watermarking technology embeds the watermark into the digital carrier by a certain algorithm.According to the research of digital watermarking and chaotic system,an im-proved image encryption algorithm based on digital watermarking is proposed in this paper.Then,based on the study of Chen hyperchaotic system and DNA computation,another image encryption algorithm is designed.1.Image encryption algorithm based on digital watermarking and chaotic system.It firstly performs row and column scrambling on the original image,then divides the image into blocks and performs block Arnold transformation on each block according to each element of chaotic matrix.For the watermark image,the watermark matrix would be padded zeros to make its size consistent with the image to be encrypted,and then row and column scrambling would be performed on it.After this,bitwise xor operation are dong with three different scrambling watermark images.Finally,each bit of every elements in the processed original image would be xor with that on the corresponding position in the final scrambling watermark image,so that the obtained image would be the encrypted image.This algorithm combines digital watermarking technology with chaotic image encryption technology,which could not only improves the security of encryption system,but also be used to judge the modified position of image when the encrypted image is illegally tampered.What is more,it uses digital watermarking to perform the pixel value substitution for the image,which effectively solves the problems of the unsecurity of just a single encryption method,matrix trans-formation,which has the difficulty to resist statistical attack.2.Image encryption algorithm based on digital watermarking and DNA calculation.It is an improvement on the previous one.Firstly,the original image is divided into blocks.For the digital watermark image,it is padded zeros and processed with row and column scrambling,then it would be divided to blocks with the same size as it of the current image.Secondly,with the initial values of the keys,the Chen hyper-chaotic system is used to generate four chaotic sequences.Thirdly,we DNA-coding the image to be encrypted and watermark image according to the rules specified in dif-ferent chaotic sequences,and then performs DNA-calculation between the two block to block according to the rules specified in one sequence,after that,we DNA-decoding the resulting matrix according to the rules specified in the fourth sequence.Finally,the order of the images's rows and columns would be scrambled then the encrypted image is obtained.Compared with the previous algorithm,this one uses DNA coding and Chen hyperchaotic system to encrypt images,which significantly improves the security of the encryption system.Eight keys means the key space is expanded and the encryption system has stronger ability to resist exhaustive attack.It can not only use digital watermark to judge the tampered position of illegally tampered image,but also improve the anti-clipping performance of the encrypted image.