Design Of Chaotic Block Cryptography And Its Applications

With the rapid development and extensive applications of information and communication technology, the security and protection of network information are becoming increasingly a key problem that must be solved urgently. Block cipher has many attractive features so that they are usually core components in information and Internet security for data encryption, data signature, authentication, and so on. Along with the launch of AES process, block cipher has become a very active subject in recent years. Autonomy is a notable feature of information security. Thus, it's very necessary to conduct block cipher research, design and development relying on our own ability.The basic principles of various chaotic ciphers based on the chaotic map and methods for designing S-boxes are analyzed in this paper at first. According to the shortcomings that the traditional methods for designing S-boxes by using chaotic maps can not find good S-boxes easily, this paper proposed a method for designing S-boxes by genetic algorithm based on the chaotic map, which design the fitness function and mutation operator on the basis of characteristics of cryptology. The method is composed of two steps. The first step is generating some S-boxes by using a chaotic map, by this way; an initial data pool can be obtained. Secondly, selection crossover and mutation would be operated on the initial data pool. The mutation is applying a Bake map several times to shuffle the table nonlinearly. In addition, the cryptographic properties such as the bijective property, the strict avalanche criterion, the nonlinearity, the output bits independence criterion and the equiprobable input/output XOR distribution are analyzed in detail for the S-box produced by the method which the paper proposed. The results of numerical analysis show that the S-box has approximately fulfilled the criteria for a cryptographically strong S-box and can resist several attacks, effectively. Based on careful analysis on the properties of the structure of various block cipher, a method combining the chaotic system and the Feistel structure is proposed to design chaotic block cipher, and the performance of this cipher is analyzed in details and is proved to have good performance of cryptology.Finally, a new database encryption scheme based on J2EE platform is discussed and implemented. The result shows that the idea of the encryption is feasible.