Research Of Image Encryption Algorithm Based On Chaos Theory

With development of information technology and increasing frequency of informationexchange, the research on information security engineering is becoming more and moreimportant. Because of the rapid development of information technology, it is becomingincreasingly difficult to maintain a satisfactory level of information security. New informationsecurity theory and advanced technologies are required urgently. Encryption is one of theimportant methods to ensure images' safety. However, on one side, most encryption methods aredesigned for text information; on the other side, some encryptions are easily to be attacked.There are many disadvantages in traditional encryptions, and a lot of encryptions for images areput forward. As a novel technology in cryptography, digital chaotic cipher has been attractedresearchers dense interest and widely studied. Chaotic dynamical system is a deterministicsystem and has random-like behavior. Since it is very sensitive to the initial conditions andcontrol parameters, a large number of uncorrelated, random-like, yet deterministic andreproducible signals can be generated easily. These properties have natural affiliations with theinformation security technology. Challenges have been set with traditional cryptography becauseof the bulk data capacity and high redundancy of widely-used patterns and multimediainformation, while chaotic cipher has great superiority over the encrypfion of multimediainformation.This thesis is first to introduce the development and relevant knowledge of chaos-basedimage encryption. Then we focus on discrete chaotic theory and its application in the area ofimage encryption and analyze some representative algorithms' merit and shortage in detail. Thena novel method of image encryption based on 3D chaotic map is proposed. The improved 3-Dcat map and coupled map lattice (CML) model are employed to design an image encryptionsystem fit for the application of real time network image encryption. Moreover, a series ofchaotic parameters are used to evaluate the performances of the proposed encryption system.The research results of this thesis prove that chaos-based image encryption technique is newencryption technique for images. Until now, a lot of research works have been made in depth andplentiful achievements have been obtained by the researchers in this field. Neverthelessconsidering the security and efficiency, there exist some deficiencies in the presentedinformation security schemes, many of which have been attacked effectively and there alsoexists much virgin field need to be dug up. Therefore it makes great sense for the research on thechaos-based image encryption technique.