Attack On JPEG Image Block By Block Mixed Wash Pixel Encryption Scheme

In the current era of increasingly convenient social information exchange,the issue of privacy has attracted more and more attention.With the rapid development of communication computer technology and the wide application of Internet in daily life,the security of multimedia data has become an important research direction.Multimedia data,including image,audio,video,etc.,has the characteristics of large amount of data,fast transmission speed,easy to be tampered with,and difficult to control,so the security problem is particularly prominent.JPEG image has the advantages of high compression rate,good image effect,supporting a variety of image formats and simple operation,so it is widely used in electronic image transmission,storage and other fields.Existing image encryption schemes may have some security vulnerabilities that can lead to attacks or decryption by cryptanalysts,resulting in the disclosure of sensitive data.The encryption scheme based on block by block mixing pixel achieves good encryption effect.The ideal JPEG image encryption algorithm should not only complete the encryption and decryption process,but also resist the common attacks while maintaining the image compression rate.This paper focuses on the security analysis of the encryption algorithm of pixel mixing block by block,finds out the defects in the algorithm,improves the original algorithm to enhance the security of the original scheme,and improves the attack algorithm on this basis to improve the speed of the attack algorithm.Based on the above analysis,the main research contents are as follows:(1)The related theory and technical basis of JPEG image compression standard and common image encryption algorithms are discussed and analyzed in depth.(2)A security analysis of a novel block-by-block mixed wash pixel-based encryption algorithm is conducted to identify the vulnerabilities of the algorithm,and a Full Chosenplaintext Attack(FCPTA)algorithm is proposed without the need of encryption key.By creating an auxiliary image,it can recover sketches with similar color and feature texture to the original image from the cipher-text image.(3)A fast attack algorithm of JPEG encryption image is proposed.In the process of adopting this new attack algorithm,only one auxiliary image is needed to get the mapping relationship of image blocks before and after encryption in most cases,all the mapping relationship between image blocks 88? could be found out,and the preliminary attack result is obtained.The non-zero number of coefficients in each 88? sub-block help to generate the attack result is,namely the final image sketch.