Application And Research Of Chaotic Symmetric Cryptography And Fragile Watermarking

People are paying more and more attention to the protection of information with the rapid development of computer and Internet in recent years. So we must find more methods to protect our information. And the chaotic system with initial value and control parameter sensitivity, pseudo randomness, ergodicity and other unique properties can provide a lot of pseudo random sequence with good randomness, which is very suitable for information security. This article proposes several new technologies by analyzing of the chaotic symmetric cryptosystem and digital watermarking system, which are as follows:(1) Design of encryption system based on multiple one-dimensional chaotic maps. Firstly we analysis the problems of encryption systems just based on only one one-dimensional chaotic map, such as small key space, precision limited caused by the problem of short cycle, and so on, and then we propose a cryptography system based on double one-dimensional chaotic maps, namely two Logistic mapping cryptography system, through the two maps to generate pseudo random sequence, which can encrypt the message, and through the analysis of the security, we find the algorithm has high security.(2) Propose an image encryption system using Game of Life permutation and PWLCM chaotic system. Points out some disadvantages of some chaotic image encryption technologies, such as using Arnold scrambling images there is limited number of iterations, application scope, scrambling after pixel position fixed, etc, on the basis of these theoretical analysis this paper proposes a new cryptographic system. We use Game of Life permutation at the confusion stage, and piecewise linear chaotic map (PWLCM) to diffuse the image, which we just process the higher half pixel to improve the speed. Finally some security analyses have been done.(3) Propose a safer fragile watermarking scheme base on the chaotic system. Analyzing a chaotic system based fragile watermarking scheme for image tamper detection which is proposed by Rawat et al, and then find a security defect. Then propose a weak watermark technology with improved. Finally some security analyses have been done.