Zhang Zirui, Chen Ping, Li Weijun, Xiong Xiaoming, Wang Qianxue, Wen Heping, Liu Songbin, Cai Shuting
School of Automation, Guangdong University of Technology, Guangzhou 510006, China.
Zhongshan Institute, University of Electronic Science and Technology of China, Zhongshan 528402, China.
Entropy (Basel). 2021 Oct 29;23(11):1431. doi: 10.3390/e23111431.
In actual application scenarios of the real-time video confidential communication, encrypted videos must meet three performance indicators: security, real-time, and format compatibility. To satisfy these requirements, an improved bitstream-oriented encryption (BOE) method based chaotic encryption for H.264/AVC video is proposed. Meanwhile, an ARM-embedded remote real-time video confidential communication system is built for experimental verification in this paper. Firstly, a 4-D self-synchronous chaotic stream cipher algorithm with cosine anti-controllers (4-D SCSCA-CAC) is designed to enhance the security. The algorithm solves the security loopholes of existing self-synchronous chaotic stream cipher algorithms applied to the actual video confidential communication, which can effectively resist the combinational effect of the chosen-ciphertext attack and the divide-and-conquer attack. Secondly, syntax elements of the H.264 bitstream are analyzed in real-time. Motion vector difference (MVD) coefficients and direct-current (DC) components in Residual syntax element are extracted through the Exponential-Golomb decoding operation and entropy decoding operation based on the context-based adaptive variable length coding (CAVLC) mode, respectively. Thirdly, the DC components and MVD coefficients are encrypted by the 4-D SCSCA-CAC, and the encrypted syntax elements are re-encoded to replace the syntax elements of the original H.264 bitstream, keeping the format compatibility. Besides, hardware codecs and multi-core multi-threading technology are employed to improve the real-time performance of the hardware system. Finally, experimental results show that the proposed scheme, with the advantage of high efficiency and flexibility, can fulfill the requirement of security, real-time, and format compatibility simultaneously.
在实时视频保密通信的实际应用场景中，加密视频必须满足三个性能指标：安全性、实时性和格式兼容性。为满足这些要求，提出了一种基于混沌加密的改进型面向比特流的加密（BOE）方法用于H.264/AVC视频。同时，本文构建了一个基于ARM嵌入式的远程实时视频保密通信系统进行实验验证。首先，设计了一种带余弦反控制器的四维自同步混沌流密码算法（4-D SCSCA-CAC）以增强安全性。该算法解决了现有自同步混沌流密码算法应用于实际视频保密通信时的安全漏洞，能有效抵御选择密文攻击和分治攻击的组合效应。其次，实时分析H.264比特流的语法元素。分别基于基于上下文的自适应变长编码（CAVLC）模式，通过指数哥伦布解码操作和熵解码操作提取残差语法元素中的运动矢量差（MVD）系数和直流（DC）分量。第三，利用4-D SCSCA-CAC对DC分量和MVD系数进行加密，并对加密后的语法元素重新编码以替换原始H.264比特流的语法元素，保持格式兼容性。此外，采用硬件编解码器和多核多线程技术提高硬件系统的实时性能。最后，实验结果表明，所提方案具有高效性和灵活性的优点，能同时满足安全性、实时性和格式兼容性的要求。
