Research On Video Security Codec Algorithm Based On Chaotic Cryptography

As a new generation of international video coding standard, H.264/AVC has been widely used in political, military, commercial, education, medical care and some other businesses. But the video was suffered from vandalism, illegal theft and digital media piracy, such as the phenomenon has been prevalent, so video data on the safety protection is receiving increasing attention. Video data has a lot of features which are large amount of data, complex coding structure and requirements of high real-time, and compressed video data is encoded in the required storage or transmission. Therefore, encryption and decryption algorithm must be designed to combine with theprocess of codec and the practical application of environment.However, many existing video encryption algorithm have three problems. Firstly, the using chaotic systems are based on floating-point operations on the real number field, both encryption and decryption will bring the problem of the key non-synchronous because of the computer word length different. Secondly, encryption algorithm will destruct video format, and can only provide a level of security. Thirdly, encryption algorithms are based on the video coding layer, adaptation layer for network-based encryption algorithm little discussion on it.Aiming at these issues, this article from the point of view of safety information, on the basis of chaotic cryptography and video compression standard, study the video of the encryption and decryption algorithm. Main task of this article are:First of all, the use of generalized cat map and the piecewise linear chaotic map construct integer domain structure of a stream cipher sequence generator, this generator overcomes the chaos of the digital word length problem effectively. Through theoretical analysis, the chaotic system has high enough security. The experimental results show that the chaotic system has a good sensitivity of the initial value, and the pseudo-random sequence has a good pseudo-random property which can make three assumptions through Golomb and the local randomness statistical test.Secondly, this paper presents a quality control and maintain the same semantic format chaotic encryption and decryption of video program at the video coding layer. From the encryption results, different levels of encryption is not the same as the degree of the video image scrambling, so it can be meet the various occasions on the security level of demand. From the test results experiment, we can see that the encryption and decryption program on the impact of encryption and decryption speed and the compression ratio have litter impact, it does not exceed 3% and 4%. So it is able to meet the requirements of real-time and less impactinn on compression ratio. In allusion to this encryption sheme, based on MFC-platform, combined with test model and used of dynamic-link library and multi-threaded, the thesis designed the encryption software system of H.264 technology.Finally, the article research the H.264 network adaptation layer ,labor the encoded bit stream format of the package, give an encryption system framework which is based on the application layer and network layer ,and the video stream encryption and decryption programs based on a code-based Analysis to the network layer, and analysis the performance of the encryption scheme.