Matthew C. Stamm (University of Maryland) “Digital multimedia forensics and anti-forensics”, 2012

Matthew C. Stamm (University of Maryland) “Digital multimedia forensics and anti-forensics”, Advisor: Prof. K. J. Ray Liu, 2012

As the use of digital multimedia content such as images and video has increased, so have the means and the incentive to create digital forgeries. Presently, powerful editing software allows forgers to create perceptually convincing digital forgeries. Accordingly, there is a great need for techniques capable of authenticating digital multimedia content. In response to this, researchers have begun developing digital forensic techniques capable of identifying digital forgeries. These forensic techniques operate by detecting imperceptible traces left by editing operations in digital multimedia content.

In this dissertation, the author proposed several new digital forensic techniques to detect evidence of editing in digital multimedia content. The thesis began by identifying the fingerprints left by pixel value mappings and showed how these can be used to detect the use of contrast enhancement in images. The author used these fingerprints to perform a number of additional forensic tasks such as identifying cut-and-paste forgeries, detecting the addition of noise to previously JPEG compressed images, and estimating the contrast enhancement mapping used to alter an image. Additionally, the problem of multimedia security was considered from the forger's point of view. It was demonstrated that an intelligent forger can design anti-forensic operations to hide editing fingerprints and fool forensic techniques. The author proposed an anti-forensic technique to remove compression fingerprints from digital images and showed that this technique can be used to fool several state-of-the-art forensic algorithms. Then, the author examined the problem of detecting frame deletion in digital video and developed both a technique to detect frame deletion and an anti-forensic technique to hide frame deletion fingerprints. It was showed that this anti-forensic operation leaves behind fingerprints of its own. The author developed a game theoretic framework to analyze this interplay and identify the set of actions that each party will rationally choose. Additionally, the author showed that anti-forensics can be used protect against reverse engineering.

For details, please contact the author or visit the thesis page.