Closed-Circuit Unobservable Voice over IP

Among all the security issues in Voice over IP (VoIP) communications, one of the most difficult to achieve is traffic analysis resistance. Indeed, classical approaches provide a reasonable degree of security but induce large round-trip times that are incompatible with VoIP. In this paper, we describe some of the privacy and security issues derived from traffic analysis in VoIP. We also give an overview of how to provide low-latency VoIP communication with strong resistance to traffic analysis. Finally, we present a server which can provide such resistance to hundreds of users even if the server is compromised.