Research On Hyper-chaotic Sequences In Bitmap Encryption

With the rapid development of information technology, more and more information is required to transfer, exchange and storage through the Internet, so that the information security has drew considerable attentions and become important in computer study. Digital image is one of the main transmission carriers, because of its intuitive, accurate transmission and easy acceptability. So people need to encrypt the important information of digital image. however, the digital images have rich information data, strong correlation between adjacent pixels and high information redundancy, therefore, the traditional encryption method is not able to meet the requirements. An image is a M ? N matrix, the image is scrambled and diffused after the decomposing.As currently used in many image encryption are low dimensional chaotic systems, and the low-dimensional chaotic encryption is vulnerable to be attacked,such as brute force attack, phase space reconstruction and so on. However,high-dimensional chaos system have many advantages of complex space structure,rich control parameters, more unpredictable exercise behavior, and that can be used for image encryption to improve the information safety. In this paper. the key is hyper-chaos system whose random performance makes the image scrambling more complex and the key space larger, then using the encryption method of block spreading to get better encrypt effect and higher safety performance.The main content of this paper :( 1) this paper summarizes the research background, significance and the present situation, and briefly introduces the chaos theory, cryptography, chaotic cryptography and other related knowledge, then introduces some commonly used methods of image encryption.(2)a kind of plane encryption algorithms are simulated and analyzed by this results, then improve the feasibility of the algorithm in the existence question of simulation diagram and the correlation data.(3) this paper verify the results. Based on the plane encryption algorithm of hyper-chaos sequence for matrix diffusion, this paper decompose the clear image into a flat by the pixel weight, then extract the required initial value ofgenerating hyper-chaos system from the clear image and obtain the key of the initial value by iterative Runge-Kutta function. Then get the matrix with the corresponding size through hyper-chaos sequence processing, in the same way to decompose bite to get key matrix. Because of high-four bit-plane contains most of the information, only deal with high four to separate scrambling operation, then integrate the scrambling high-four plane with low-four plane to obtain the scrambling consolidation matrix,and is divided into 2 ? 2 block to diffuse. Finally, the cipher-text security is tested,results show that the cipher-text has strong sensitivity to the key and plain-text, and can effectively resist various attacks, which verify the effectiveness of security confidentiality in the scheme.