The Study Of Information Security System Based On Chaos Theory

Today computers are used everywherer, and the information are transported in public channel. Then how to insure the information safe and integrated become more and more important than before. Nowadays, the computer technology develop rapidly and the operation-speed of computing components become faster and faster. So attacker can translate the cryptograph successfully within less time and cost. Thus the study of information security system is a popular subject in this information era.The phenomena of chaos is a determinate and random process in non-linear dynamics system. From 80', the chaos was used in secrecy systems, specially in chaos-sequence encryption. The secret-key generated by chaotic system show the excellent characteristic of cryptology. and this method can predigest the traditional design course. So chaotic encryption is a important cryptology in modern information security system.This dissertation is based on the theory of cryptology and chaos. And this dissertation used the characteristic of chaotic sequence and combined chaotic map and encryption theory to construct information scurity system. The main achievements and originalities in this dissertation are as follows:①This dissertation discuss the development status in quo of chaos, set forth the different definiens of chaos, describe the non-linear dynamics characteristic of chaos, and expound judgment rule of chaos. This dissertation also indicate the chaos theory can be used in information security system via the studying, analyzing of chaos theory.②The security of traditional one-tine-pad cryptosystem is analyzed, and point out that the limit of computing speed should reduce the security though the one-tine-pad cryptosystem is the only one security encryption can be proved by mathematic technique. Thus,some issues which should be considered are presented.This dissertation applyμ-generator to expand the periods of secret-key, and analyse the elements and structure ofμ-generator . The security analyses prove this method can enlarge space of the secret-key, and ensure the security of ciphertext.③The security of chaotic sequence is analyzed, and point out that the chaotic sequence would appear the pseudrandomicity when there have no enough iterative precision. To solve this problem, this dissertation use non-linear dynamics characteristic of neural network to implement diffusing and mixing of sequence, and construct a neural network with forefeedback channels to avoid the chaos neural network get into infinitesimal. The security analyses and the experiment prove the secret key dealed with the neural neywork has good randomocity.④The security of block cryptosystem and the feasibility of using chaotic theory in block cryptosystem are analyzed, and point out that the traditional S-box in block cryptosystem is static and irrespective with encryption process. To solve this problem, this dissertation applied bidirectional chaotic map to construct S-box. The analyses and the experiment prove this S-box is dynamic, random and has good cryptological characteristic. The system can resist outer attack impactfully.Finally, the research works of this dissertation are summarized, and the future developing directions are indicated.