Cell phone camera ballistics: attacks and countermeasures

Abstract

Multimedia forensics deals with the analysis of multimedia data to gather information on its origin and authenticity. One therefore needs to distinguish classical criminal forensics (which today also uses multimedia data as evidence) and multimedia forensics where the actual case is based on a media file. One example for the latter is camera forensics where pixel error patters are used as fingerprints identifying a camera as the source of an image. Of course multimedia forensics can become a tool for criminal forensics when evidence used in a criminal investigation is likely to be manipulated. At this point an important question arises: How reliable are these algorithms? Can a judge trust their results? How easy are they to manipulate? In this work we show how camera forensics can be attacked and introduce a potential countermeasure against these attacks.