Research On The Chaotic Signal Via Random Processing

With rapidly development of science and technology, information security problem becomes of much more importance in both frontier field of science and common daily life. Chaotic theory is one of the most famous science foundations in 20 th century, and chaotic signal is applied in information security and secure communication research because of its sensitivity to initial conditions, till now it becomes one of the main research in this field. Recently, there have been some developments in chaotic signal research, and chaotic signal with better randomness characteristics is the basis to realize information security and secure communication, moreover, chaotic signal can be divided into three types, low-dimensional chaotic signal is generated from difference iterative equation, high-dimensional chaotic signal is generated from ordinary differential equation and digital chaotic signal is generated from quantization scheme, etc. This thesis does randomization researches on different chaotic signals, comparing with stochastic theory to do researches, which proposes comparison research of low-dimensional chaotic signal and randomness, improves the marked feature of high-dimensional chaotic signal, constructs digital chaotic new model based on stochastic model to improve randomness of output sequences, and finally designs an application research based on traditional cipher code algorithm in chaotic encryption module. The main research is as follows:Firstly, it is the research on the low-dimensional chaotic signal via random processing, and such signals are generated from difference iterative equation, and due to its characteristics like stochastic signal, comparing with random variable and random process, this thesis proposes chaotic quasi-random variable and chaotic quasi-random process with their statistical analysis, meanwhile, it proposes random chaotic system and its sample assumption model, exploring its input-output characteristics through different random distributions and different chaotic signal.Secondly, it is the research on high-dimensional chaotic signal via random processing, according to the obvious features of traditional Lorenz signal in time and frequency domain, this thesis proposes the frequency domain FFT truncation method which can improve the obvious features, furthermore, it proposes the improved chaotic masking secure communication scheme for simulation application with its improved parameter analysis.Thirdly, it is the research on digital chaotic signal via random processing, and it analyzes basic conditions to construct digital chaotic new model based on degeneration characteristics of digital chaotic signal, and do the exploration research through the random modeling point of view, this thesis proposes the HMM-based digital chaotic new model scheme with their analysis in statistical sense, moreover, it demonstrates that the output digital sequences have better randomness through different randomness test indexes.Finally, it is the application research on the chaotic signal random processing, in order to satisfy cipher requirement in real application, combined with traditional cryptography algorithm to design chaotic encryption module, this thesis proposes and realizes the short message hardware encryption system based on FPGA, through the experimental tests it can indicate that this system can send and receive short message from common cell-phone, as well as the encrypted short message safely. Meanwhile, it summarizes the whole researches to show the outlook work in future.In conclusion, this thesis proposes some researches about chaotic signal randomization so that the randomness of chaotic signal can be improved, and it proposes different solution schemes for different chaotic signal based on random theory. Combined theoretical analysis with simulation experiments, this thesis provides the basic exploration research plan of chaotic signal randomization.