A Novel Sketch Attack for H.264/AVC Format-Compliant Encrypted Video

In this paper, we propose a novel sketch attack for H.264 advanced video coding (H.264/AVC) format-compliant encrypted video. We briefly describe the notion of sketch attack, review the conventional sketch attacks designed for discrete cosine transform (DCT)-based compressed image, and identify their shortcomings when applied to attack compressed video. Specifically, the conventional DCT-based sketch attacks are incapable in sketching outlines for inter frame, which is deployed to significantly reduce temporal redundancy in video compression. To sketch directly from inter frame, we put forward a sketch attack by considering the partially decoded information of the H.264/AVC compressed video, namely, the number of bits spent on coding a macroblock. To evaluate the sketch image, we consider the Canny edge map as the ideal outline image. Experiments are conducted to verify the performance of the proposed sketch attack using ICADR2013, High Efficiency Video Coding dash, and Xiph video data sets. Results suggest that the proposed sketch attack can generate the outline image of the original frame for not only intra frame but also inter frame.