The Research Of Secure Communication Technology Based On Hyper-chaotic Stream Ciphers

With the improvement of army's informatization, a lot of sensitive information transmits through network, for example: image, video and so on. When certain departments investigate the scene, the image of scene transmits without any security precaution. Therefore, a novel effective method needs to be exploited to enhancement the security of image transmission.It's different from text-data, image data and video data are largeness and often processing in real-time. So, traditional encrypt algorithms are not appropriate for image data. Stream cipher is simple to realige, encrypt rapidly, and lower error diffusivity. So, it's more adaptable to the requirement of image and real-time and largeness data.Based on the studing of the modern cryptology theory, this thesis analyses the performance of 3-dimensional hyper-chaotic Henon mapping in periodicity, pesudo-randomness, and sensitivity to initial condition and system parameters, Lyapunov exponent, power spectral density, and so on. The result shows that hyper-chaotic sequence has complexity, unpredictability, pesudo-randomness, and good distributional performance. It is a perfect tool of encryption for secure communication.Main contents of this thesis are as follows:1. It proposes an encryption method which uses the general Henon mapping of hyper-chaos to generate data series, and disturbs them by low-dimensional Logistic mapping to generate stream cipher.2. It analyses the relations of general Henon mapping divergence speed with the parameter and the initial-value, then analyses the relations between chaos and the parameter by the Lyapunov exponent. It gives the new numeric area of parameter: 1.55< a< 1.8, 0<|b|<0.2, the initial-value takes in (- 1.5, 1.5), which provides the rules to choose the key space of hyper-chaotic stream cipher.3. It studies the performance of anti-statistical analysis by testing the random, complexity properties, encryption efficiency of novel sequences. The experimental result indicated that, the novel sequences have the good characteristic of cryptology.4. A method of image encryption is designed and realized based on the Cat mapping and multidimensional hyper-chaos in this thesis. The analysing of attack-protection performance shows that the method is practical, highly effective, and good characteristic of cryptology.This thesis lays the foundation for application of hyper-chaotic cipher by researching for the relations of general Henon mapping parameter and the key space.