The Study And Implementation Of Chaos Ciphers

Along with the continuous development and the rapidly growing popularity of information technology, the problem of information security is becoming increasingly prominent, it has been become an important issue of the normal operations of the national economy and national security. Cryptogram is the core of information security, chaos-based Encryption is a new research direction of Cryptogram. In this dissertation, at first, some cryptogram elements, the chaos theory and the history of the development of the chaos were introduced, the relationship between chaos theory and the related traditional theory was preliminary summarized and analysised. On the base of analysising the problems in the process of producing Digital Chaos in theoretically, the dissertation analyzes that the problem of quality of balance result by the uneven distribution of Logistic Map used in the chaos-based Encryption. Then, the diploma thesis pointed out that this was not consistent with the principle of diffusion which is one of the two basic principles of coaching password design provided by Shannon, besides, the dissertation analyzed and described the problem by using of the method of data experimentation, then, brought forward a number of measures for improving the performance and lay out its capability by using of computer simulation, On this foundation, chaos cryptography was designed and carried out, the dissertation also described safety analysis and experiments.The main achievements contained in this dissertation are as follows:Firstly, combining cryptography theory, the theory of pseudo-random sequence, the non-linear theory, linear complexity theory, complex system theory and stochastic theory , this dissertation summed and described chaotic cryptography and their relations.Secondly, the performance degradation issues of the limited accuracy that Chaos Ciphers was achievement on computer systems were analysied. Then some propose appropriate measures were brought forward to reduce the effects of limited accuracy and improve their safety and availability. Combined Logistic Map, based on a lot of data testings and analysis, propose measures to improve the performance were brought forward and analysied.Thirdly, based on the existing theoretical analysis and data analysis, according to the measures for improving the design of the system, Multi-Chaotic Ciphers was designed and achieved, then, a security analysis and the experiments of encryption and decryption were accomplished.