Image Encryption Method Research Based On Chaos Theory And Wavelet Transformation

With the continuous development of information technology, digital image communication has become a common means of information and communication. How to ensure secure transmission of information in a digital image communication, become a hot research topic. Image communication contains large amount of information but high redundancy. The traditional cryptographic algorithms cannot encrypt the image communication very well. Chaotic systems, with the basic characteristics of uncertain, pseudo-randomness, unpredictability and sensitivity to initial conditions, can well meet the requirements of cryptography, therefore, it is very suitable as a carrier of secure communication to encrypt digital image. Based on the basic theory of chaos theory and wavelet transformation, this article made an in-depth study of the application of chaos theory in image encryption. It also proposed two image encryption methods, and designed hardware-based systems and software development processes based on chaotic encryption algorithm.This article first made a basic introduction of basic theory and research background of chaos, including the concept of chaos, key technology and main measure of characteristics and etc. It focused on baker mapping and other scrambling algorithm, and based on this, proposed an image encryption algorithm based on chaotic binary sequences and improved Baker mapping. Binary sequences can further expand the key space relative to ordinary chaotic sequence. Improved Baker mapping can expand the size of the image to general rectangle. Finally, use the Matlab to simulate the algorithm. The simulation results show that the algorithm takes full advantage of the chaotic sequence of scrambling and diffusion characteristics, and get a good encryption effect.Secondly, the paper studied the basic theory of wavelet transformation, including the basic concepts of Wavelet Transformation and two-dimensional discrete wavelet applied in image processing. Based on this, this paper presents an encryption method based on chaotic sequence and wavelet transform, in addition, use Arnold mapping to diffuse the image, then get the encrypted image from wavelet reconfiguration. Through the simulation results, the algorithm can be well used in encrypting digital image, and can also be able to resist noise attack and the cropping attack, meanwhile, it has a strong anti-decipher and higher operating efficiency.Finally, this paper analyses and summarizes the system requirements and design ideas, designed a hardware and software systems based on chaotic image encryption method. The hardware system is composed of the memory module, input and output modules, LCD modules and power modules with the core DSP processor. Besides, chose TMS320DM642as DSP chip according to the requirements. Software system includes a framework for the entire system and the corresponding software modules, and design the software development process for the two algorithms proposed in this paper.