Study And Realization Of Digital Chaotic Cipher

With the development of the multimedia and digital communication, people hold more and more information and communicate much more easily. For the security of information, it is necessary to protect it from eavesdropper. Although there are different demand for the cipher in different application, but security and speediness are the essential.Dynamical chaotic system with instability and noisy-like orbit is difficult to predict, some research have pointed out that there exists tight relationship between chaos and cryptography. But it is insecurity to construct the cryptography with chaotic system directly and for digital system, it is impossible to realize the real chaotic system because that the chaos is defined in continuous real number. In digital system, it is called digital chaotic system. To construct a cipher method with high speed and security, this paper worked on the following aspects:Firstly, in paper introduce the character of the chaotic system and analyze the feasibility to design cipher base on the digital chaotic system. And some weakness is pointed out in digital chaotic ciphers have been published.And then, the paper study the pseudo random number generated by digital chaotic system and make some modifications on the chaotic iteration. These modifications can improve the weakness of digital chaotic system effectively, such as short-cycle and beyond control of digital chaotic sequence, statistical degradation of chaotic system, concealing system information and low processing speed.Last, based on the Digital Signal Processor(DSP), the paper realize an applied encryption system. Jt connected with host by Universal Serial Bus(USB) interface. The project can be integrated with other applications of multimedia and digital communication easily to ensure the security of information.With the primary analyze and the experimentation, the project of this paper obtains the good purpose of digital chaotic cipher.