Security in voice over IP

This dissertation is the product of a research project3, which focuses on the study of VoIP protocols' security issues. It starts with the review of the three VoIP protocols. Then, it introduces some common security concepts used in VoIP security. After that, the dissertation concentrates on the study of SIP security. The build-in security mechanisms of SIP protocol are investigated. Two general security solutions for SIP protocol, that is, PGP/MIME and S/MIME, based on Public Key Infrastructure (PKI), are reviewed and analyzed. We further point out their advantages and disadvantages for SIP security. In order to overcome the disadvantages of these two solutions, a new solution for SIP security is proposed. The new solution makes use of the One-Time Password (OTP) scheme on the application layer and the TLS scheme on the transport layer. It can provide both access control service for call participants and authentication/confidentiality service for SIP messages.Master of Science (Communication Software and Networks