Western University Scholarship@Western Electronic Thesis and Dissertation Repository 2-2-2011 12:00 AM Architecture Supporting Computational Trust Formation Chern Har Yew University of Western Ontario Supervisor Hanan Lutfiyya The University of Western Ontario Graduate Program in Computer Science A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Chern Har Yew 2011 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Systems Architecture Commons Recommended Citation Yew, Chern Har, "Architecture Supporting Computational Trust Formation" (2011). Electronic Thesis and Dissertation Repository. 86. https://ir.lib.uwo.ca/etd/86 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. .ARCHITECTURE SUPPORTING COMPUTATIONAL TRUST FORMATION (Spine title: Architecture Supporting Computational Trust Formation) (Thesis format: Monograph) by Chern Har Yew Graduate Program in Computer Science A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada © Chern Har Yew 2011 THE UNIVERSITY OF WESTERN ONTARIO School of Graduate and Postdoctoral Studies CERTIFICATE OF EXAMINATION Supervisor Examiners ______________________________ ______________________________ Dr. Hanan Lutfiyya Dr. Michael Bauer Supervisory Committee ______________________________ Dr. Robert Mercer ______________________________ Dr. ______________________________ Dr. Victoria Rubin ______________________________ Dr. ______________________________ Dr. Ferhat Khendek The thesis by Chern Har Yew entitled: ARCHITECTURE SUPPORTING COMPUTATIONAL TRUST FORMATION is accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy ______________________ _______________________________ Date Chair of the Thesis Examination Board ii Abstract Trust is a concept that has been used in computing to support better decision making. For example, trust can be used in access control. Trust can also be used to support service selection. Although certain elements of trust such as reputation has gained widespread acceptance, a general model of trust has so far not seen widespread usage. This is due to the challenges of implementing a general trust model. In this thesis, a middleware based approach is proposed to address the implementation challenges. The thesis proposes a general trust model known as computational trust. Computational trust is based on research in social psychology. An individual’s computational trust is formed with the support of the proposed computational trust architecture. The architecture consists of a middleware and middleware clients. The middleware can be viewed as a representation of the individual that shares its knowledge with all the middleware clients. Each application uses its own middleware client to form computational trust for its decision making needs. Computational trust formation can be adapted to changing circumstances. The thesis also proposed algorithms for computational trust formation. Experiments, evaluations and scenarios are also presented to demonstrate the feasibility of the middleware based approach to computational trust formation. Keywords trust, experience, recommendation, reputation, signal, belief, architecture, middleware iii Acknowledgments I wish to express my sincere gratitude towards my supervisor, Dr. Hanan Lutfiyya. Her guidance, encouragement and friendship are instrumental in my completion of this work. Other professors that have helped me along the way include Dr. Michael Bauer and Dr. Mark Perry. As for fellow distributed systems research group colleagues, special thanks needs to be directed towards Brad Simmons (graduated), Raphael Mafita Bahati (graduated), Gaston Keller and Zainab Aljazzaf. iv Table of Contents CERTIFICATE OF EXAMINATION ........................................................................... ii Abstract .............................................................................................................................. iii Acknowledgments.............................................................................................................. iv Table of Contents ................................................................................................................ v List of Tables ..................................................................................................................... xi List of Figures .................................................................................................................. xiii List of Appendices ......................................................................................................... xviii Chapter 1 ............................................................................................................................. 1 1 Introduction .................................................................................................................... 1 1.1 Current Use of Trust in Computing ........................................................................ 1 1.2 Computational Trust ............................................................................................... 3 1.2.1 Foundational Research ................................................................................ 3 1.2.2 Definition .................................................................................................... 4 1.2.3 Properties .................................................................................................... 6 1.2.4 Conceptual Model ....................................................................................... 9 1.2.5 Trust Formation ........................................................................................ 12 1.3 Application of Computational Trust ..................................................................... 13 1.3.1 Movie Selection Scenario ......................................................................... 13 1.3.2 Web Service Selection Scenario ............................................................... 14 1.4 Challenges to Computational Trust ...................................................................... 17 1.5 Contributions of Thesis ......................................................................................... 18 1.6 Thesis Organization .............................................................................................. 19 1.7 Summary ............................................................................................................... 20 Chapter 2 ........................................................................................................................... 21 v 2 Trust Primer ................................................................................................................. 21 2.1 Preconditions for Trust ......................................................................................... 21 2.2 Concepts Related to Trust ..................................................................................... 21 2.2.1 Untrust, Distrust and Mistrust ................................................................... 22 2.2.2 Trustworthiness ......................................................................................... 22 2.2.3 Contract ..................................................................................................... 23 2.2.4 Confidence ................................................................................................ 23 2.3 Privacy .................................................................................................................. 24 2.4 Risk ....................................................................................................................... 25 2.5 Decision Making ................................................................................................... 26 2.6 Summary ............................................................................................................... 26 Chapter 3 ........................................................................................................................... 27 3 Literature Review ......................................................................................................... 27 3.1 Survey of Trust and Reputation ............................................................................ 27 3.1.1 The World Wide Web (WWW) ................................................................ 27 3.1.2 Peer-to-Peer (P2P) Networks .................................................................... 30 3.1.3 Virtual Communities ................................................................................. 34 3.1.4 Pervasive Computing Environments......................................................... 38 3.2 Middleware Support for Computational Trust Formation .................................... 39 3.3 Survey of Trust Middleware ................................................................................. 40 3.4 Summary ............................................................................................................... 41 Chapter 4 ..........................................................................................................................