We are interested in security of emerging and current systems. Our research involves design/implementation of novel attacks, and developing countermeasures against such attacks. We currently focus on 1) security issues for Cyber Physical Systems (CPSs) such as medical devices, smart grid, and automobiles, 2) control plane security of mobile/ad hoc/sensor/cellular networks, Internet, P2P systems, 3) Penetration testing of Korean cyber infrastructure, and 4) other security issues such as cloud/storage security, anonymous communication systems and censorship-resistant systems.