A Distributed Key-Changing Mechanism for Secure Voice Over IP (VoIP) Service

Voice over IP (VoIP) has experienced tremendous growth in recent years due to its low cost and flexible service enhancement. However, it is vulnerable to security attack. The most popular solution to providing secure VoIP service is based on the advanced encryption standard (AES). The practice for AES-based solution is to adopt a common secret key negotiated during a VoIP call setup phase. This single common key solution is, however, vulnerable to many kinds of attacks. In this paper, we propose a distributed multi-key solution which dynamically changes the encryption key based on the Diffie-Hellman algorithm to provide more secure protection for an end-to-end VoIP call. The proposed mechanism does not need to renegotiate new keys during a call and is robust to network dynamics and packet losses. Most importantly, it incurs small delay overhead comparable to the solutions with encryption protection. The performance of the proposed mechanism is evaluated via laboratory experiment, and validated by some security analysis.