<title>Content-dependent video authentication by self-watermarking in color space</title>

Abstract

A plausible motivation for video tampering is to alter the sequence of events. This goal can be achieved by re-indexing attacks such as frame removal, insertion, or shuffling. In this work, we report on the development of an algorithm to identify and, subject to certain limitations, reverse such acts. At the heart of the algorithm lies the concept of a frame-pair [f,f*]. Frame-pairs are unique in two ways. The first frame is the basis for watermarking of the second frame sometime in the future. A key that is unique to the location of frame f governs frame-pair temporal separation. Watermarking is done by producing a low resolution version of 24-bit frame, spreading it, and then embedding it in the color space of f*. As such, watermarking f* is tantamount to embedding a copy of frame f in a future frame. Having tied one frame, in content and timing, to another frame downstream, frame removal and insertion can be identified and, subject to certain limitations, reversed.