The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


"Anonymous and Trustworthy Computing in Peer-to-Peer Systems"

By

Mr. Jinsong Han


Abstract

Peer-to-Peer (P2P) model has become the mainstream of the applications in
current and future Internet. Being effective in utilizing and managing
globally distributed information over Internet, however, most current P2P
systems do not provide protection to their users against the increasing
threat from selfish peers or malicious adversaries. Anonymous and
trustworthy computing hereby has continuously gained importance because it
meets the users' demands of privacy, fairness, trust, and reliability. In
order to construct anonymous and trustworthy P2P systems, we must address
several crucial challenges including 1) reliably and efficiently
anonymizing the P2P network; 2) authenticating users' identities; 3)
enabling trust management in anonymous environments. Most existing
approaches achieve anonymity via fixed paths, which are unreliable and
inefficient in dynamic P2P systems. We propose two non-path based
protocols to anonymize P2P systems. The results of trace driven
simulations show that our proposed protocols are reliable, scalable and
effective, and significantly reduce cryptographic overhead. The second
issue is that the current authentication approaches face a dilemma in
anonymous environments: authenticating other users needs their real
identities; while the anonymity requires those users to hide their real
identities.   We propose a Zero-knowledge based protocol to allow users
authenticate with each other without exposing their real identities. We
show the effectiveness of our proposed protocol by simulation studies and
prototype implementation. We solve the third issue by constructing a
reputation based trust management architecture. We particularly focus on
the feedback quality problem. In shorting of trusted authority centers in
P2P systems, the feedback quality are easily wrecked by the dishonest
feedback from malicious peers, which further degrades the computation
accuracy of users' reputation. Our proposed architecture effectively
alleviates the damage on computing reputation caused by the feedback
cheating. We believe that widely employing above proposed approaches will
make P2P systems more secure and reliable. We also extend our study to
other distributed systems and propose a privacy-preserving authentication
protocol for RFID systems.


Date:			Wednesday, 4 July 2007

Time:			10:00a.m.-12:00noon

Venue:			Room 3501
			Lifts 25-26

Chairman:		Prof. H.B. Peng (BIOL)

Committee Members:	Prof. Yunhao Liu (Supervisor)
			Prof. Lionel Ni
			Prof. Qian Zhang
			Prof. Weichuan Yu (ECE)
			Prof. Chung-Ta King (National Tsing Hua U, Taiwan)


**** ALL are Welcome ****