Study On Video Encryption Algorithms Based On H.264

With the rapid development of multimedia and network technology, the application scope of multimedia video has expanded to almost all walks of life such as politics, economy, military affairs, education and so on. While some sensitive occasions such as politics, economy, military affairs and so on have the high demand for confidentiality and security. So, it's necessary to encrypt these sensitive video data to ensure their security, and study on video encryption technology is of great significance.As video information has the characteristics of great data quantity, high demand for real-time, special coding structure and so on, we need to design special encryption algorithms for these features in order to ensure the security of video information, to meet the real-time property and compression ratio invariance, and to maintain the data format requirements. As selective encryption algorithms can meet these requirements well, they have been widely researched and applied currently, and this kind of encryption algorithms is also the research focus of this dissertation.This dissertation introduces the new international video encoding standard H.264 and its coding structure characteristics, studies video encryption algorithms in recent years and the analysis & summary is given. On this basis, we propose and implement two new selective encryption algorithms. The main jobs we complete are as follows:(1)We introduce and summarize the related situation of video encryption and H.264 standard. And this lays the foundation for research on video data encryption.(2)We propose an improved Intra prediction mode (IPM) encryption algorithm (IPMEA). It encrypts all the IPMs by chaotic pseudo-random sequence, scrambles them for the second time by circulating sequence controlled by key. It can exhibit higher security than the existing ones and has little impact on code length. Meanwhile, it has low complexity and good real-time property, so it is suitable for real-time video transferring on the network.(3)For H.264 video encoding standard, we propose a new encryption algorithm for DCT coefficients. It combines shuffling with layered scrambling within a block, that is, it treats macro block (MB) as the basic unit for encryption, shuffles the 4×4 blocks within a MB randomly at first, and then scrambles the layered DCT coefficients within the MB. Performance analysis and experimental results show that this algorithm has good encryption effect and is suitable for secure network applications based on H.264.