The Research Of Video Hyperchaotic Encryption Based On ARM

Generating chaotic or hyperchaotic signal with good performance is the key of secure communication and information encryption. The security of chaotic cryptography system depends on the complexity of chaotic signals, and the more complex structure and behavior of hyperchaos used to generate the cryptography sequence can enhance the security of the system. Digital cryptosystem (chaotic encryption and digital chaotic communication) is tide of chaotic cryptography, but there are problems of the dynamical degradation such as short-length chaotic orbits. Synchronization and the speed of signal generation and encryption are the keys of chaotic application and many methods are raised to solve them, but they are difficult to meet the requirements of the chaotic synchronization in actual channels. These have become the obstacle that chaotic theory is applied to the application. Based on these problems, to improve the complexity of cryptography sequence, a new hyperchaotic system is designed and a kind of digital implementation method is studied. A chaotic sequence extraction method is proposed, which not only improves the rate of chaotic sequences generated but also overcomes the degradation of digital dynamics. Then the PR (pseudo-random) sequence statistical properties is tested. The paper implements a chaotic encryption network monitoring system, in which practical methods are proposed to solve the synchronization,disordered UDP transporting and the encryption speed problems. The main work of this thesis is:(1) Based on a given chaotic system, a new hpyerchaotic system is constructed by introducing a non-linear item. The detailed dynamical behaviors of the new systems are further investigated, including equilibrium and stability, various attractors, bifurcation analysis and Lyapunov exponents'spectrum. Comparing the experiment with the simulation on Matlab, it is shown a good agreement between numerical simulations and experimental results.(2) In order to produce the PR sequence to meet the digital chaos encryption system requirement, this thesis applies FPGA-based technology and ARM-based technology for implementing a continuous chaotic system in digital form. A model of descteting and quantizing the continuous chaotic system is established and the constructed hyperchaotic system is descreted. Then the chaotic PR sequences are generated with this method. The performances of the PR sequences are analyzed by NIST, and the result shows that the sequence has good performance, and can be used in encryption system.(3) The thesis designs a web-based video transmission and encryption system, including video capture, chaotic encryption and decryption, network transmission, video display and other modules. In this system, multi-threaded programming is introduced to improve the efficiency of chaotic sequence generation and encryption; In the UDP transmission modules, the packets are numbered and the buffer pool for sorting received packets are introduced to solve the disorder problem. To solve the synchronization problem, in chaotic encryption and decryption module, each packet is encrypted as a separate file, and encryption system parameters and initial values are set according to the number of the packets.(4) The security of the encryption system are analyzed, including the key space, sequence performance, the key sensitivity, statistical analysis of attack, known plaintext attack and chosen plaintext attack. Analyzed results show that the system has a good security.