Jongil Jeong

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.

VoIP SPAM Response System Adopting Multi-leveled Anti-SPIT Solutions

VoIP spam will become severe problem preventing from generalization of VoIP service. For comprehensive response against spam, this paper implemented VoIP SPAM response system adopting multi-leveled anti-spam solutions. To adopt them, we divided VoIP service domains into three domains as outbound, intermediary, and inbound. The main goal of anti-spam solution in outbound domain is to prevent spam by monitoring and detecting call traffic of registered users. In intermediary domain, we focused on blocking SIP message forgery spam using SIP-based sender policy framework. Inbound domain has the “easy spam reporter”. This module enables victims to report spam contents to the administrator directly. The reported contents and information, of course, are shared with other domains as a black list. Through the experimental result, we showed this system is enough to prevent, detect, and block VoIP spam.