Research On Video Encryption In Compressed Domain Based On HEVC Bitstream

With the rapid development of telecommunication industry and popularity of internet, various multimedia technologies, like image, video, are comprehensively used in our life. In the meanwhile, the security issues of multimedia information are getting increasingly prominent. With the convenience it brings, there are a lot of potential safety hazard. Due to the open and data-sharing of the internet, multimedia information is extremely susceptible to be stolen and manipulated in the process of storage and transmission. Therefore, the security issues of video are getting more and more attention.Video encryption is an efficient approach to protecting the multimedia information. However, owing to video's huge volume, sophisticated codec structure and strict real-time requirement, video encryption cannot process like conventional data encryption Consequently, video encryption algorithms must be specifically designed according to particular video codec. Various demands such as format compliance, security, computational complexity and the impact on compression efficiency should be taken into account. Therefore, in this paper, based on the up to date HEVC coding standard, research on video encryption in compression domain is carried out. The main research includes:Firstly, based on the structure of HEVC bitstream, a format-compliant video encryption algorithm is proposed. At first, it's confirmed that the selected syntax elements used for encryption are in coding unit layer. Through deep analyzing of context adaptive binary arithmetic coding, the syntax elements after binarization are firm to be encrypted. To avoid affecting the compression efficiency, only those syntax elements using bypass mode while processing binary arithmetic coding can be choose for encryption. Six syntax elements are selected for encryption through further analysis of the characteristic of five different binarization ways. The experimental results show that, the proposed algorithm can provide sufficient security while keeping the format-compliant and coding efficiency unchanged of the encrypted stream. It can also resist the replacement attack and brutal force attack.Secondly, a codeword-sensitivity based video encryption algorithm for HEVC stream is proposed. In this part, the codeword-sensitivity of each selected HEVC syntax element is tested. Based on the results, the priority of encryption is ordered. The syntax elements with high codeword sensitivity are encrypted firstly, which ensuring the syntax elements that are essential to video reconstruction can be encrypted primarily and improve the pertinence of encryption algorithm. The experimental results shows that, comparing with SE-HEVC, the proposed algorithm can get enough security with low computational complexity.Thirdly, a quality-controlled perceptual video encryption scheme is proposed. At first, the syntax elements most associated with perception are selected as encryption data. Then, the texture and motion characteristics of the video sequence are analyzed through the information extracted from HEVC bitstream, such as motion vector, prediction residue and so forth. According to the analysis result, the encryption videos are classified into different categories. Based on the classification of different video sequence, a quality control factor Pc was difined to control the percentage the encryption data in different syntax elements, so that we can control the perceptual quality of the encrypted video and provid different perceptual qualities for different users.