Lawful Interception Scheme for Secure VoIP Communications Using TTP

This paper proposes lawful interception scheme for secure VoIP (Voice over IP) communications using TTP (Trusted Third Party). The proposed scheme is that TTP creates a master key and send it to VoIP terminals, and VoIP terminals create session keys for media traffic encryption using master key. TTP sends session key to law enforcement agency for decrypting encrypted media traffic. This scheme enables to do lawful interception and restrict the ability of law enforcement agency because the session key only validates during one session.