The Impact of Confidentiality on Quality of Service in Heterogeneous Voice over IP Networks

With the advent of ubiquitous access to multimedia content via wireless networks, users are more likely to have their data traverse a heterogeneous internetwork. Given the open nature of the Internet and wireless links, more users will demand end-to-end confidentiality. However, because of inherent error-expansion properties of secret-key encryption, it is a challenge to provide good subjective quality and end-to-end confidentiality for multimedia data, particularly in network environments subject to both loss and corruption impairments. This paper analyzes the affect end-to-end confidentiality has on the quality of service (QoS) in Voice over IP (VoIP) networks. To satisfy a given QoS objective, we show that mitigating the error-expansion caused by confidentiality comes at a cost. We measure this cost by increased delay, reduced bandwidth, and reduced traffic capacity. Thus, for this class of applications, we motivate the need for error-robust encryption and introduce one such technique in this paper.