Research On Chaotic Secure Communication System

Information security is an important problem in information times. With the development of computer technology, encrypted systems are cracked from time to time although classical cryptography is effect to protect information safety. Now it is urgent to create a new encryption mechanism or a new way to guarantee information safety. Chaotic systems are able to be assume this important task due to its natural. Recently chaotic secure communication is one of hot topics in the field of information security. In this dissertation, several key issues in chaotic secure communication are researched and some chaos-based communication schemes are proposed as well, which are detailed as follows: 1.Backstepping-based synchronization of a disturbed uncertain chaotic system is researched, and chaotic secure communication is proposed which is able to define the attacks of reconstructing attractor and return map. Unified form chaos is taken as an example. Backstepping-based identical chaotic synchronization is established and secure communication scheme is investigated which is combined with chaotic mask and chaotic modulation. Backstepping-based general chaotic synchronization is set up and secure communication basing general synchronization is studied and the plant is put forward which is consists of chaotic mask and chaotic modulation. In order to improve complexity of communication systems, cellular neural network taking unified form chaos as neuro is founded and its identical synchronization and general synchronization are researched. And sufficient conditions of identical synchronization and general synchronization for cellular neural network are achieved via backstepping mechanism. And the cellular neural network chaos is used to design secure communication system with high security, real time property and parallel processing. 2. Security problem of observer-based chaotic secure communication is researched. The communication scheme with high security is obtained, which defines attacking from adaptive synchronization and ciphertext chosen. Furthermore, the secure communication with robustness is investigated in order to improve communication system's and chaotic sequence's sensitivity to parameter changed. The secure communication system with high safety and real time property is set up. 3. The problem of fuzzy chaotic chaos with structure uncertainty and external disturbance applied to communication is researched. Synchronization conditions are attained, which is high robust and does not need nonlinear terms in chaotic systems being Lipschitz continuous. Then secure communication scheme combined with traditional cryptography is brought forward, which can define attacking from attractor reconstructed and optimal strategy parameter- identification-based. 4. Lag synchronization of uncertain time-delayed chaotic systems is studied. Sufficient conditions of lag synchronization in time-delayed chaotic systems are attained. And secure communication schemes basing lag synchronization comprising single chaotic system and several chaotic systems are established. The schemes resist attacks of reconstructing attractor and optimal strategy parameter-identification-based. 5.Generalized synchronization based chaotic communication is studied. By use of impulsive differential equation theory, sufficient conditions for generalized synchronization are obtained. The structure of generalized synchronization based chaotic communication is proposed, where ciphertext contains synchronization impulse, drive chaos state and response chaos state during a periodic so that some attack methods are invalid, such as reconstructing attractor, adaptive identification and optimization-based identifying parameters, etc. Therefore system security is improved. At same time, due to robustness and real time property of control method, secure communication system is characterized by high robustness and good real time property. 6. Chaotic cryptographic is researched and chaotic map-based encryption/decryption algorithm for image is proposed. Use standard...