| With the continuous progress of science and technology, information technology has penetrated into every aspect of people's lives. Information security has attracted more and more attention, and so how to strengthen information privacy becomes an urgent and important problem. On the one hand, H.264 standard for video compression become a research hotspot because of its high compression ratio and good network of affinity. On the other hand, because of chaotic signals'inherent non-periodic, broadband spectrum, sensitive to initial values and other prominent features, it makes chaotic signals'pseudo-noise (PN) sequence has random and long period characteristics, which makes chaotic system has a good application prospect in the encryption of information. In order to enhance the confidentiality and practicality of chaotic information encryption, the following two aspects are needed to do first: improving the performance of chaotic sequence and improving the performance of encryption system. Based on that background, This paper implement chaotic video encryption at the stage of CAVLC entropy coding of H.264 coding standard by using logistic map to generate chaotic sequences as the encryption key. And a series of new results are got as follow:(1)Serveral chaotic systems are systematically studied. The generation of chaotic sequence is the premise and the key technology of using the chaotic sequence in the information encryption technology. In this paper, several typical chaotic systems are studied, including continuous and discrete chaotic system. The dynamic behaviors of these chaotic systems are analysised, including bifurcation characteristic and Lyapunov exponent's spectrum. Besides, the analog circuit of the chaotic system is also designed. Comparing the experiment with the simulation, it shows that the practical attractors got from experiment are the same as theory, which also verifies the nature of chaotic system.(2)The performances of logistic chaotic sequence are analysised. Considering the chaotic encryption communication used in engineering, it is necessary to construct a good chaotic system with excellent performance. From the initial analog circuitry to current digital systems, it produces a series of new problems with the continuous development of chaos. This paper summarizes the previous research and analysis the performance of logistic discrete chaotic system. The results show that logistic chaotic sequences is suitable as an encrypted key sequence, and these researchs are play an important roles for the continuous in-depth study in the future.(3)A video encryption system based on CAVLC (Context-based adaptive variable length coding) entropy coding is designed. CAVLC entropy coding can be used in the various grades of H.264 coding standard, so it can be used for all services that associated with the h.264 encoding standard such as video conferencing, security monitoring, digital broadcast television, streaming media and so on. As the video encryption based on entropy coding is considered to be the trend of the video encryption, this study has important practical significance.(4)Using Logistic chaotic sequence, the scheme of chaotic video encryption and decryption based on H.264 coding standard is implemented. The bit-stream of each frame of video is encrypted in the phase of CAVLC entropy coding of H.264 coding by using logistic chaotic sequences as the key stream. Then we analysis the security of this encryption algorithm, the encryption efficiency and other aspects. The results show that the encryption algorithm is very sensitive to the key and the key has large space which can resist to a variety of attacks. So this encryption system has high security. Besides, encryption in the phase of entropy coding does not change the structure of the stream, and its encryption speed is very fast. Therefore this encryption system has a very good real-time character and good application value. |
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