A reputation system for BitTorrent peer-to-peer filesharing

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University of Wollongong Research Online University of Wollongong Thesis Collection 1954-2016 University

Lan Yu University of Wollongong Recommended Citation Yu, Lan, A reputation system for BitTorrent

thesis, Information Technology and Computer Science, University of Wollongong, 2006. http://ro.uow.edu.

1 University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 2006 A reputation system for BitTorrent peer-to-peer filesharing networks Lan Yu University of Wollongong Recommended Citation Yu, Lan, A reputation system for BitTorrent peer-to-peer file-sharing networks, M.Comp.Sc. thesis, Information Technology and Computer Science, University of Wollongong, Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: research-pubs@uow.edu.au

3 UNIVERSITY W OF OLLONGONG A Reputation System for BitTorrent Peer-to-Peer File-sharing Networks A thesis submitted in fulfillment of the requirements for the award of the degree Master of Computer Science by Research from UNIVERSITY OF WOLLONGONG by Lan YU Faculty of Informatics August 2006

5 Dedicated to My family iii

6 Declaration This is to certify that the work reported in this thesis was done by the author, unless specified otherwise, and that no part of it has been submitted in a thesis to any other university or similar institution. Lan YU August 31, 2006 iv

7 Abstract Over the past few years, Peer-to-Peer (P2P) networks have grown extensively and dramatically changed large-scale file transfer. One of the most popular P2P network is the BitTorrent system. BitTorrent can efficiently distribute large files by optimizing the use of network bandwidth and providing scalability. Due to the open and anonymous nature of P2P systems BitTorrent also provides an ideal environment for distribution of malicious, low quality, or doctored information. A number of reputation systems, including P2PRep with its successors XRep and X 2 Rep, had been proposed to address security weaknesses of Gnutella P2P file sharing networks. Although it has been claimed that these methods are also applicable to the other file sharing networks, it is not clear how to achieve this task. Moreover, some of the shortcomings of these reputation systems such as online-polling only and cold-start may be exploited by malicious attackers. In this paper, we propose a reputation system, called X 2BT Rep, which is an extension of the X 2 Rep and for BitTorrent network. We show that the proposed system improves the security and the quality of information distributed over P2P networks. v

8 Acknowledgements First of all, I would like to make a grateful acknowledgement to Rei Safavi-Naini, my supervisor, for pointing me to the right direction on my research, Network Security in Peer to Peer System. During this research, she provided me many valuable advices and constant support. Also, my sincere appreciation goes to Willy Susilo, my co-supervisor, for his guidance through the past two years of chaos and confusion on my study and life. Moreover, I am thankful to Juliet Richardson, International Study Program Coordinator, for her carefully reading the draft and offering grammar correcting and writing suggestions. Additionally, my thanks go to all staff in my Faculty, School of Information Technology and Computer Science, for their offering many facilities, including space,soft and hardware, telephone, etc. to support my research. Furthermore, I appreciated my family and friends for their encouragement helping me to finish this research. vi

9 Publications L. Yu. X 2BT Rep trusted reputation system: A robust mechanism for P2P networks. HDR Student Conference, University of Wollongong, Australia, August L. Yu, W. Susilo, and R. Safavi-Naini. X 2BT Rep trusted reputation system: A robust mechanism for P2P networks. The 5th International Conference on Cryptology and Network Security, China, August vii

10 Contents Abstract Acknowledgements Publications v vi vii 1 Introduction Aims and Objectives Structure of the Thesis Our Contribution Glossary Notations Peer-to-Peer: Now and the Future What is a P2P Network? Generational Evolution of P2P Networks First Generation Centralised P2P Second Generation Decentralised P2P Third Generation Hybrid P2P Current Developments Advantages and Weaknesses of P2P Networks Summary Previous Studies of Reputation Systems Introduction ebay P2PRep XRep X 2 Rep viii

11 3.6 Credence Summary Overview of BitTorrent Network Introduction Architecture Protocol Specification Bencoding Metainfo File (.torrent file) Tracker HTTP protocol Peer TCP Protocol Strengths of BitTorrent Shortcomings of BitTorrent Distribution of false information Man-in-middle attack IP harvesting Summary A Robust Reputation Management System X 2BT Rep Introduction Principle of our Management Model Assumptions Distributed Repositories Voting Centralised Repositories Secure Sockets Layer Further Discussion of Two Novel Algorithms Credibility Award Algorithm Credibility Chain Exchange Protocol Designs Initialisation Phase: Enhanced Torrent Creation Phase 1: Torrent Search Phase 2: Exchange of Votes Phase 3: Votes Evaluation Phase 4: Tracker Queries Phase 5: Pieces and Credibility Chain Exchange ix

12 5.4.7 Phase 6: Updating and Voting Reputation Value Summary Critical Evaluation of X 2BT Rep Introduction Assessment of X 2BT Rep Attacks on BitTorrent-like systems Defection attack Poisoning attack & Insertion of viruses in carried data Denial of service attack Malware software in BitTorrent networks Identity attack Spamming Attacks on Reputation-based Systems Pseudospoofing Reputation spoofing Whitewashing attack Reputation attack by collectives Referral attack Summary Implementation and Interpretation of Experiment Introduction Implementation of X 2BT Rep in the BitTorrent Environment X 2BT Rep Extensions to BitTorrent Repository Schema Additional Protocol Messages Experiment I. Intention of Experiment II. Experiment Setting III. Working Principle IV. Malicious Strategies V. Simulation Result VI. Conclusion of Our Experiment Comparison with other Reputation Systems Summary x

13 8 Conclusions and Future Work 81 Bibliography 84 xi

14 List of Tables 2.1 The definition of five descriptors in the Gnutella protocol The basic polling protocol in P2PRep system The enhanced polling protocol in P2PRep system The X 2 Rep reputation system protocol The summary of various trusted reputation mechanisms The summary of a comparison between X 2BT Rep and other trust reputation mechanisms xii

15 List of Figures 2.1 First Generation Centralised P2P Architecture Sequence of operations in the Napster protocol Second Generation Decentralised P2P Architecture Sequence of operations in the Gnutella v0.4 protocol Third Generation Hybrid P2P Architecture BitTorrent Architecture A glance at torrent files of Linux from mininova.org web page Sequence of messages in enhanced torrent creation phase Number of active peers over time (sourced from [26]) Sequence of messages and operations in X 2BT Rep protocol BitTorrent s Information Flow with X 2BT Rep protocol extensions Basic working principle based on a genuine resource and honest clients Working principle based on a milicious resource and honest clients Working principle based on a malicious resource and several dishonest pollers Simulation results in different situations xiii

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