Partial encryption by randomized zig-zag scanning for video encoding

In this paper, a novel partial encryption method for video encoding is proposed. For video compression based on block transforms, two zig-zag scan orders can be used which provide similar compression performance. The proposed method involves randomly selecting one of these two scan orders. In addition, the sign bit of the DC coefficients can be flipped randomly and when employed with the proposed method provides a much better scrambling effect. In comparison to previous work in this area, experimental results based on H.264/AVC show that the proposed method can scramble the video with very minimal impact on the compression performance.