An object-based unequal encryption method for H.264 compressed surveillance videos

Multimedia information security has become a research hot topic in recent years. In this paper, an object-based unequal encryption method for H.264 compressed surveillance videos is proposed on the basis of bit-sensitivity analysis of bitstream. In the proposed method, moving object detection and segmentation is performed first, thus location information of the objects can be directly extracted from the H.264 bitstream. Then object regions and background in the surveillance video are encrypted unequally. The bits with the highest sensitivity in the macroblocks covering the object region are thoroughly encrypted while those in the background macroblocks are selectively encrypted. Experimental results have shown that the proposed object-based unequal encryption method is able to effectively ensure the security of surveillance scenes, while the required complexity is low. Furthermore, object detection and encryption are entirely operated in the compressed domain and the output encrypted bitstream remains format-compliant with H.264 standard and the compression ratio can also be maintained.