Research, Telemetry Information Security Technology Based On Chaos Theory

Under the rapid development of information technology, the security of information has attracted more and more attentions in recent years. Especially for the important information of the Reentry Telemetry system, what technology is adopted to ensure these data information transmitted safely to the destination during the data is transmitted in open space, and how to make the non-authorization side can't understand the true meanings even if they can intercept these signal. This is a very important question. In these years, along with the development of the theory and application of chaos, many researchers are now focusing on the chaotic cryptography and information hiding based on chaotic theory. Nevertheless, considering the security and efficiency, there also exist some deficiencies in the presented information security schemes.In this thesis, we study mainly the information security based on the discrete chaotic systems, including the Reentry Telemetry PCM data and the pulse signal. Finally we establish the simulation platform of the PCM data encryption and decryption base on chaotic theory. As well as the information secure transmitting of the pulse signal in the Reentry Telemetry system is also investigated, for example the Chaotic Pulse Position Modulation technology.The main work and research results of this thesis lie in the following:1. Stream cipher mode will be ensured to encrypt the Reenter Telemetry PCM data, by comparison quantificational the block cipher (for example:DES) the stream ciphers. The error diffusion can be avoided in receiver if the PCM data is encrypted by stream cipher.2. A newly chaotic mathematics model has been put forward. That is HYBRID mapping. The characteristic of the HYBRID mapping is analysized, especially the phase trajectories near critical points, the stability of HYBRID system, and the timing perturbation approach is applied remedying the finite precision. The standard statistical tests demonstrate that the generated key stream has a random-like behavior,δ-like auto-correlation function and near-zero cross-correlation function. Next, the chaotic key stream is realized by using the Digital Signal Procession (DSP). The results shows that the chaotic key stream has excellent the statistic properties, and can be easily realized. It can be fit for encrypting PCM data.3. Based on chaotic theory, a simulation platform of the PCM data encrypted/decrypted in Reenter Telemetry is built. In this system, the synchronous scheme of the working key in both transmitter and receiver sides is designed. This method provides a realizable way for "one-time pad" in some sense. So we have solved successfully the reliability and the robust of the working key in receiver, and analyzed the security of the cipher system. At last this system is tested under the multi-path Rayleigh fading environment. MATLAB simulation shows the diffusion of error bit isn't arise. Of course, the encryption intensity of the Reentry Telemetry PCM secret system is assured. In a word, some helpful reference can be provided for the realization of the Reentry Telemetry PCM secret system.4. The system experiment of PCM signal based on chaotic encryption/decryption has been validated. Especially aiming at the unique demand of the high-speed flying object, we have designed a scheme of chaotic encryption. By use of the Channel Fading Simulator, We have realized the chaotic decryption in receiver. In conclusion, some fruitful explore have been obtained by the experiment.5. The theory of Chaotic Pulse Position Modulation and Demodulation is researched. On the basis of the theory, we have discussed and simulated the information secure transmitting technology of the pulse signal in Reenter Telemetry system. A new thought about the pulse signal encryption/decryption in Reenter Telemetry system can be provided from the theory.6. The application of chaotic theory is discussed in spread spectrum communication fields. On the basis of a sort of newly chaotic mapping, we describe detailly the generating approachs of chaotic spreading sequence. Some criteria on optimizing spreading sequences and the method of choosing are also presented. By numerical simulation, the correlation and balance property of the chaotic spreading sequences are analyzed. Calculation shows that the pseudo-random character and the linear complexity are excellent to Logistic mapping, and these optimized chaotic spreading sequences are much better than Gold sequences. The results of this work are also useful reference to the Telemetry multi-objection system.Finally, the research work of this paper is summarized, and the future developing direction based on chaotic theory in Reenter Telemetry field is indicated.The dissertation was supported by the Science and Technology Fund of the China Academy of Engineering Physics{Subject Number:20050429), and the National safe Academic Foundation (NSAF, Grant No.10776016).