The Research Of Chaotic Speech Secure Communication System Based On UDP/IP Protocol

With the development of the Internet, more and more recognition has been paid to the security of information. How to secure the secrecy of information transportation appears to be the chief problem. Chaotic system has complex dynamic characteristics, and its chaotic signal has lots of performance such as high sensitive to initial value, noise–like characteristics and so on. So it has good application prospect in secure communications. In order to improve the practicability of chaos in secure communications, chaotic sequence and its synchronization are the key of secure communications. However, hyperchaos systems have more complex structure and behavior. Using the hyperchaos sequence can improve the security of information transmission. Chaotic synchronization is the key technology of secret communication, and many synchronization methods have been presented in the theory. But it is difficult to realize chaotic synchronization in the practical information transmission, which has become a great obstacle in the practical chaotic communications. This paper makes a series of research works, and obtains some relevant results on the research background. The main works of this thesis are as follows:(1) Based on the Sprott system, an improved chaotic system is constructed by introducing a non-linear. The detailed dynamical behaviors of the new system are further investigated, including equilibrium and various attractors, stability, bifurcation analysis and Lyapunov exponent'spectrum. Besides, and its simulating chaos circuit is designed. Comparing the experiment with the simulation. It is shown that the attractor of the new chaotic are the same, which also verifies the nature of chaotic systems(2) In order to improve the complexity of chaotic system, based on the Lorenz system, this thesis presents a novel hyperchaos system and its basic dynamical behaviors are further investigated. Furthermore, a corresponding circuit of the hyperchaotic system is also designed and simulated by using the EWB software.(3) In order to realize the digital sequence of chaotic system, a chaotic system is implemented in digital form using analog and digital circuits. Quantitation of chaotic and hyperchaotic system are mainly investigated based on FPGA. In the research two systems are discretized with DSP Builder software, and practical chaotic digital sequences are obtained from FPGA. In order to obtain good digital random sequences, the random performance of the generated sequences is tested by using NIST test package. Its performances accord with the NIST test standard and are suitable for secure communications. (4) This paper studies a chaotic sequence synchronization method which is based on UDP/IP-based protocol synchronization on Linux plant. A chaotic speech secure communication scheme based on UDP/IP-based protocol synchronization and simplex is designed and realized under Linux environment. And the experiment testing is performed and experimental results are analyzed.