Overview of Networking Research

1. Overview of Networking Research Richard Yang

2. Overview • There are many activities going on; here I only sketch some of my projects related with the ubiquitous-access vision:, cost-effective way.” “People and their machines should be able to access information and communicate with each other easily and securely, in any medium or combination of media – voice, data, image, video, or multimedia – any time, anywhere, in a timely, cost-effective way.” • Improve availability by peer relay and mobile agents • Improve efficiency by using secure multicast • Improve battery life by applying DVS scheduling

3. Improve Availability by Peer Relay: PARCelS [Zhou, Yang ‘02] • Protocol overview: • base stations announce congestion indications • route discovery messages can be dropped to reduce load to congested regions • use the AIMD algorithm to achieve adaptive load-balancing

4. Incentive Design for Peer Relay • Problems of peer relay: peer nodes have no incentives to relay other’s traffic because relay will use their resources such as bandwidth and battery • Solutions: • reputation-based system, • e.g., [Marti et al. 2000; Liu & Yang ‘03] • credit-based system Sprite [Zhong, Chen & Yang ‘03] • Design requirements of a credit-based system • be incentive-compatible, i.e., users receive the right amount of credit for their actions • prevent group collusion

5. distributed verifiable oblivious transfer Improve Availability by Mobile Agents • Motivation: use mobile agents as delegates of users to improve availability • Design requirements of a mobile-agent system • be secure: a malicious host machine or a server cannot compromise the security of the mobile-agent program • be efficient • Solution: Secure Mobile-Agent Computation with Threshold Trust [Zhong and Yang ’03]

6. Improve Bandwidth Efficiency by Secure Multicast • Motivations: - multicast turns wireless disadvantage into advantage - however, not all users should have access to the content - solution: encryption using secret key - problem: dynamic user population causes problems - forward secrecy: departed users have no access to future communications - backward secrecy: new users have no access to past communications - naïve solution: whenever user population changes, send each user a new key encrypted by the user’s own key • [optimal]solution: using a key-tree to solve access control problem [Wong et al. 1998, Yang et al. 2001, Zhang et al. 2004]

7. k1-9 k123 k456 k789 k1 k7 k2 k3 k4 k5 k6 k8 Scalable Secure Multicast Using Key Trees (changed to k1-8) {k1-8}k123 {k1-8}k456 {k1-8}k78 (changed to k78) {k78}k7 {k78}k8 k9 u2 u1 u3 u4 u5 u6 u7 u8 u9 can be extended to a key graph to model multiple security groups

8. leave join registration rekey encoding individual keys rekey transport Keygem: Scalable Reliable Rekeying

9. An Integrated Approach to Apply DVS to Mobile Devices • Motivations: - the supplied voltage of mobile processors can be adjusted to save power - previous solutions: - operating system community: average-case, soft real-time; therefore jobs can miss their deadlines - real-time community: worst-case, hard real-time, specific for different schedulers (RM, EDF); do not consider that jobs may finish before the worst case estimation power voltage x D • solution: a unified scheme to computeoptimal scaling policy, independent of schedulers M w

10. Other Projects and Remarks • There are many other projects going on at Yale, e.g., - selfish routing [LYZS03]; probabilistic routing [Xie, et al. ‘03] smart routing; heterogeneous congestion control; layered multicast - localization [Eren et al. ‘03]; routing using mobility [Goldenberg, et al. ’03] policy on wireless spectrum sharing • There are many students and faculty who are interested in networking-related research - we are always looking for interesting problems - we are always looking for external support