Analysis And Designs Of Digital Image Encryption Algorithm Based On Chaos

Along with rapid development of network technique, sharing and transmission ofinformation has become increasingly convenient and fast. Admittedly, it is convenientfor people. However, security risks are brought inevitably at the same time. Digitalimage, due to its intuitive, vivid and other characteristics, has become one of the mostwidely used digital information in the fields of politics, economy, military, education etc.Like other digital information, digital image is also faced with increasingly serioussecurity threat. Therefore, there is an urgent need for protection of security andconfidentiality in digital image storage and transmission process, and cryptography is akey technology to solve the problem of information security. Digital image has thefollowing characteristics, large amount of data, high correlation, large data redundancyand two-dimensional distribution of data. The use of conventional encryptiontechnology will not only cost a lot of computing resources, but also will lead to theimage information leaks and other security issues. Chaotic system has thecharacteristics of initial value sensitivity, ergodicity, parameter controllability andpseudo-randomness. Owing to the natural link between cryptography and chaoticsystem, it can provide new ideas for the study of digital image encryption algorithm.In this paper, a research on digital image encryption algorithm based on chaos wasconducted. By analyzing the defects of the security and practicality in the existingencryption algorithms, a new digital image encryption algorithm was designed based onthis. The following aspects are the main work of this paper:①Research status concerning image encryption based on chaos was summarized.Relevant theoretical knowledge of chaos and cryptography was introduced. A briefanalysis on the relationship between chaos and cryptography was performed. Thecharacteristics of the digital image and the current encryption mode for digital imagesand safety evaluation standards were analyzed. Design thought, design philosophy anddesign procedure of the existing digital image encryption algorithm based on chaoswere summarized in order to lay the theoretical foundation of analysis and design of thedigital image encryption algorithm based on chaos.②Through the cryptanalysis of a new image alternate encryption algorithm basedon chaotic map was carried out and it was improved efficiently. Firstly, the implieddefects of algorithm on safety and practicality were pointed out and an effective improved algorithm was proposed. Then simulation and security analysis of theimproved algorithm were performed and comparison with the original algorithm wasconducted. The results show that the the safety and practicality of improved algorithmare better than the original algorithm.③Through the cryptanalysis of a general representative significant‘permutation-diffusion’ image encryption based on chaos, it was found that there is awidespread design flaw in the algorithms. Based on this, a novel Bit-plane imageencryption based on chaos was designed. Images were divided into higher informationcontent4-bit images and lower information content4-bit images and different strengthencryptions were carried out, respectively. Simulation and security analysis results showthat the algorithm is not only faster in encryption and decryption, but also has bettersecurity and practicality.