Chaotic Network File Password System

Generation of digital chaotic sequences and the achievement of the Chaotic Cryptography Encryption Algorithm are two basic parts of the application of chaotic cryptography in information security. Based on the application of the encryption with chaos, this dissertation does some deep and detail studies on the generation of chaotic pseudorandom (PR) sequences and the design of chaotic encryption software with VC++. And the achievement is not only a practical exampple of the chaos application in information security, but also has extremely significant for the application of chaotic sequence in engineering practice. The main contributions of this dissertation are as follows:(1) In the cryptology field, an excellent key generator should produce good performance of the key with the ability to quickly generate the key. Based on the noted Chua system, the new chaotic systems which are n- scrolls can be constructed with more complex dynamics by introducing the different construction of function f. The detailed dynamical behaviors of the new systems are further investigated, including equlibria and stability, various attractors and bifurcation analysis. Besides, the analog circuits of the new systems are also designed. Comparing the experiment with the simulation, it is shown that the attractors of the new chaotic system are the same, which also verifies the nature of chaotic systems.(2) In order to overcome the problem of degradation of the digital chaotic system dynamics, based on the double precision of the chaotic ciphers, The fourth-order Runge - Kutta method of the chaotic system is used which can obtained the non-destructive discretization. Then, the PR sequences are obtained according to the popular sampling method. At the mean while, in order to ensure the resulting key can meet the confidentiality requirements, the relative performance testing is needed, such as the randomness property, the run property and so on. According to the result of the characters comparison between the chaotic sequences and standard value, the performences of the chaotic PR sequences are excellent.(3) In order to improve performance of chaotic sequence encryption security, some methods of chaotic encryption algorithm are deeply studied. Chaotic Key Stream encryption algorithm is implemented based on the respective strongpoint of chaos and the stream algorithm. For the chaotic sequence has an infinite key space and the stream algorithm is simple, the encryption performance is perfect and fast. According to the properties of chinese characters, a file encryption algrithm based on searching is designed.(4) A chaos-based network file encryption system is designed as an application of chaotic encryption. This system has the characters such as cipher text high security, convenience of key management , key transport security and so on.