Digital watermarks for audio integrity verification

Abstract

This paper proposes a new method of detecting and locating manipulations of audio recordings, such as cuts, inserts, replacements or muting of selected audio segments. The objective is to verify (or dispute) integrity of audio recording in business applications (such as business conducted over the phone), court depositions, journalistic interviews, etc. We assume that embedders are public, residing within audio recorders, while extractors are secure (forensic). For this application we propose a combination of watermarks, including spread spectrum and replica watermarks, resulting in high robustness to erasure and overwriting attacks, and good localization of modified intervals. We also propose pseudo-random stego key hopping as protection against overwrite attacks. Finally, we discuss possible alternative applications of the proposed techniques.