Digital Color Image Encryption Based On Chaos And Its Software And Hardware Implementation

With the increasing popularity of the Internet, image, voice, video and other multimedia digital information communication has become more and more open, free and international, which appeared in the information security problems of various kinds. For digital image information, because of its large amount of data, high redundancy and strong correlation characteristics, making previous general encryption methods are not effective. With the development and deepening of the research on Chaos theory, people found that there is a strong relationship between chaos theory and cryptography. Chaotic cryptography provides a new solution for the security of multimedia information such as digital images.A digital color image encryption algorithm based on high dimensional extensive hyper chaotic cat map is designed and realized in this paper. The algorithm is based on chaotic system which has a series of characteristics, such as randomness, wide spectrum, extreme sensitivity of the initial state and structural parameters and so on, and consider the characteristics of digital color image data and combined with the characteristics and requirements of cryptography. The algorithm firstly is the R, G and B components of original digital color image are arranged, and then scrambling pixel coordinates by using two-dimensional extensive cat map and diffusing the value of pixel by using eight-dimensional extensive cat map for the processed image. After two processes of scrambling and diffusion are alternating many rounds, encrypted image is obtained by splitting processed image and integrating R, G and B components. The high dimensional extensive cat map has two positive Lyapunov exponents, belonging to the hyper chaotic map. So it can further improve the effects of scrambling and diffusion, and the arrangement of R, G and B components will greatly to improve the security of image encryption.To illustrate the performance of the designed algorithm which applied to the digital color image encryption, firstly, using the software of MATLAB to simulated realize the image encryption and decryption algorithm. Then the algorithm of the key space and image statistical characteristics, including histogram and adjacent pixels correlation, and the snow avalanche effect of key were tested and analyzed by it. The results of experiments verify the feasibility, security and confidentiality of the algorithm. Finally using the development platform of DSP that the chip model is TMS320DM6437 to carry out some related tests for the digital color image encryption and decryption algorithm. The results of implementation of the DSP hardware and the time of image encryption and image decryption in this paper verify the real-time performance and practicability of the algorithm.