Abstract
Designing selective encryption (SE) algorithms for H.265/HEVC video has drawn extensive attention. However, most SE algorithms without bit rate increment encrypt only the motion vector difference (MVD) and residual in the bypass mode, which makes them unable to provide a satisfactory level of security. In this paper, we present a chaos-based SE scheme for H.265/HEVC video, which reaches a balance between bit rate and security. To provide a large visual distortion, nine syntax elements of context-based adaptive binary arithmetic coding (CABAC) are selected for encryption. Their values are masked using a keystream sequence generated by the chaotic system to ensure real-time constraints. For the syntax elements containing both regular-coded and bypass-coded bins, we propose new encryption approaches with no bit rate increment, whereas the existing methods all increase the bit rate. In addition, we also suggest an encryption method for the residual sign when the sign bit hiding (SBH) technique is enabled. Experimental results indicate that the proposed algorithm has a bit rate increment of 0%, as well as provides a key space of size 2212\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2<^>{212}$$\end{document} and average PSNR and SSIM below 11dB and 0.26, respectively. Compared with the state-of-the-art HEVC SE algorithms, our suggested scheme not only offers a higher level of security but also keeps the same bit rate.