Research On Color Image Encryption Algorithm Based On Chaotic System

Digital image is a kind of important form of the multimedia information, the information whichconveys is direct-viewing and vivid. With the development of Internet and multimedia technology, digitalimage is widely spread in the network and has become one of the main mode of information expression.Accordingly, how to protect the secure transmission of digital image in the open network environment hasbecome a hot research spot in the field of information security.The digital image has characteristics such as a large amount of information, the adjacent pixels strongcorrelation the information redundancy etc., so the traditional encryption algorithms are not suitable forimage encryption.Because its extreme sensitivity, ergodicity, pseudorandom properties about initial valuesand parameters, the chaotic system is very suitable for digital image encryption.Compared with thetraditional image encryption algorithm,image encryption algorithm based on chaos has unique advantagesin dealing with large amounts of data and reducing the redundancy information in the image. Therefore, thechaotic image encryption technology is widely studied now.In view of the present status of research, this paper design high efficiency and security digital imageencryption system by using high dimension chaotic system,hyperchaotic system, spatiotemporal chaoticsystem and the fractional order chaotic system and then verities the safety of these encryption system fromthe aspect of the key space, key sensitivity, histogram, correlation of adjacent pixels and differential attackby simulation experiment.The main work in this paper is as follows:Firstly, we propose a color image encryption algorithm based on a new three-dimensional chaoticsystem.The algorithm improves the complexity of the diffusion process of cipher systems and ensures thesecurity of encryption algorithm by using XOR (exclusive or), additive, mod (calculating residue) and othermode of operation in the diffusion process.Secondly, we propose a new color image encryption algorithm based on hyperchaos system. Thisalgorithm scrambles each part of the pixels of the plain image randomly. Then it scrambles the whole pixelsof each color components.Finally it changes the pixel value of the image by using the chaotic key. Analysisshows that a few rounds of scrambling and diffusion circulation can obtain good encryption effect.The simulation experiment shows that the proposed algorithm has the advantages as good encryption effect,high safety and less time cost.Finally, we propose a robust color image encryption algorithm based on spatiotemporal chaotic systemand the fractional-order chaotic system. This algorithm shuffles the image of each color component. Theparameters and initial value of chaotic system which are generated by using280bits long external keygenerate chaotic sequence.It uses spatiotemporal chaotic sequences to scramble the plain image and usesthe fractional order chaotic sequence to deal with the scrambled image. Experiment results show that thealgorithm has good encryption effect, furthermore, it has the strong robustness with the common imageprocessing operations such as adding noise, cropping and rotation, etc..