Comparison of digital audio watermarking techniques for the security of VOIP communications

In this paper, the authors present digital audio watermarking techniques that can be used for source origin authentication in real-time Session Initiation Protocol (SIP) Communications, such as Voice over IP (VoIP). The watermark-enabled VoIP mechanism utilizes audio watermarking techniques as a covert channel between calling parties to send source origin indicator information during the transportation phase of VoIP. The effects of audio watermarking were measured using the Signal-to-Noise Ratio, watermark extract durations and the effects of a-law, u-law and GSM encoding during the transportation phase of VoIP. Moreover, various audio watermarking algorithms were implemented to demonstrate the applicability of aforementioned security solution in terms of certain parameters: robustness, evaluation times, complexity and capacity. The experimental results suggest that some watermarking algorithms are applicable in VoIP, while others are not suitable for source origin authentication.