The Research Of Image Encryption Technique Based On Chaos Series And Rsa Algorithm

In information times today, with the rapid development and wider application of the network technology and multimedia technology, more and more information has been quickly and conveniently transmitted through the network, but at the same time it has also brought the problem of information security. Therefore, how to protect information security has become a hot topic in international studies. Encryption technology is the most effective means of protecting information security, and has become a very practical and urgent essential technology to need development rapidly.The research of image encryption based on chaos theory has been a hot topic in recent years. On one hand, the traditional encryption methods have some flaws, such as the key space of DES under the current computer's speed is too small and RSA encryption is too slow; On the other hand, with the development of information technology, the demand of the rapid and efficient image encryption algorithm for network applications has become increasingly urgent. And the chaotic series has some excellent characteristics of cryptography, such as the pseudorandom, initial value sensitivity, long-term unpredictability and so on. To combine chaotic series and digital image encryption technology can construct a very good image encryption system, so the research of chaotic theory is of vital significance to image encryption.This paper discusses some chaos theory's methods and some encryption technology in cryptology, and then study deeply the essence, features and performance of the chaos theory and cryptography analysis technology. With describing the chaotic systems of the Lorenz, Duffing2 and Chens in detail and researching many literatures of image encryption based on chaotic system, this paper found that the parameters of discrete chaotic system is rare generally, the key space is relatively small. Therefore using the chaotic series generated by the low-dimensional discrete chaotic system to encrypt the images information, although it has excellent visual effects, the encryption security is not high, and it is easy to be cracked. This paper proposed finally a image encryption algorithm based on the LDC composite chaos system that using three three-dimensional chaotic systems of the Lorenz,Duffing2 and Chens generates three composite chaotic systems to enhance chaotic system's security and also improves the three chaotic systems in order to make the chaotic series with characteristics of 0,1 uniform distribution and better image histogram. In order to solve the security problem of the keys to the composite chaotic system in the management and transmission, this paper encrypts the keys to chaotic systems using the RSA encryption algorithm with high security.In order to speed up image transmission speed in network applications and to reduce disk storage space in image management applications, this paper compresses the encrypted image. Through the study of three transform technologies for the S+P transform,integer DCT, lifting wavelet transform and the four coding algorithms for RLE coding, LZW coding, Huffman coding, arithmetic coding and the thorough research of the three image compression algorithms for the EZW,SPIHT,EBCOT arigothm,and aims at the unique characteristics of encrypted image with uniform distribution of 0 and 1, this paper improves the EBCOT algorithm for better compression performance to the encrypted image and analyzes comparatively with the EZW, SPIHT and EBCOT algorithm. Finally this paper demonstrates that the improved EBCOT algorithm has characteristics with high compression ratio and compression speed by experiments.