The Research Of Stream Cipher Based On Chaos

Chaos is a ubiquitous nature phenomenon. The solution of chaos mathematical model is an extremely instable movement localized on finite space. The long-term behavior of system exhibit chaos and the time space average of system shows typically randomness. So the signal generated by iteration of simple chaos mathematical model get the feature of randomness. All these good natures make chaos widely used in the field of secure communication.The chaotic phenomenon is the foreland and hot topic in both theory study and project application. Up to now,the theory researches about chaotic phenomenon are mature. There are many chaotic models that produce the chaotic sequences, such as Logistic map, Tant map, Cat map, Piece wise Linear map. The application researches about chaos are to the fields of data encryption and secure communication. Many researches have been done to create pseudo-random binary sequence which can be a substitute of conventional sequence.The work deals with the problem on how to generate random sequences with long period and good randomness. The main work involves:(1)Having investigated the development of traditional sequence encryption indicated the necessary conditions required for secure cipher and given out the generation designing principles and judging standard.(2)Having proposed stream cipher quasi-chaotic sequence of the combination of chaos and sequence cipher, and given out the principles of the generation of stream cipher quasi-chaotic sequence and analyzed the randomness period of it. Under the experience , a new methord of generateing a quasi-chaotic sequence is showed, also the new methord gave a good way to improve the problem which is brought on by the finite data length effect of computer.(3)A new design of stream cipher Yamb algorithm is show there. It combines chaos theory and stream cipher theory. The design gets a more sensitive,more complexity and randomness sequence by changing the LFSR to chaos map. The method is implemented by soft/hard ware, and prove that the new algorithm has a satisfactory character.