Often copyrighted multimedia files are uploaded and shared online. To avoid the unregulated spread of such material many copy detectors have been developed in order to deny the possibility to upload, and consequently make available, copies of copyrighted contents. A widely referenced fingerprint method for content-based audio identification is the Philips Robust Hash (PRH) . This paper introduces a simple but effective attack technique capable to defeat a PRH fingerprint-based audio copy detector without significantly affecting the signal quality.
It is a heuristic method that adds a suitable distortion to the original audio signal, so that the modified signal is not detected as a copy of the original one but is perceptively very similar to it. The quality of the modified signal has been evaluated in terms of a distortion measure based on a mathematical model of the human auditory system and of the Peak Signal-to-Noise Ratio (PSNR). The attack method has shown a promising success rate.