Worcester Polytechnic Institute Electronic Theses and Dissertations Collection

Title page for ETD etd-092905-183353

Document Typethesis
Author NameWhitney, Justin D
Email Address ripple at alum.wpi.edu
TitleThe Wisdom of Crowds as a Model for Trust and Security in Peer Groups
DepartmentComputer Science
  • Fernando C. Colon Osorio, Advisor
  • Murali Mani, Reader
  • Michael A. Gennert, Department Head
  • Keywords
  • threshold cryptography
  • file sharing
  • security
  • peer to peer
  • p2p
  • trust
  • Date of Presentation/Defense2005-09-26
    Availability unrestricted


    Traditional security models are out of place in peer networks, where no hierarchy ex- ists, and where no outside channel can be relied upon. In this nontraditional environment we must provide traditional security properties and assure fairness in order to enable the secure, collaborative success of the network. One solution is to form a Trusted Domain, and exclude perceived dishonest and unfair members.

    Previous solutions have been intolerant of masquerading, and have suffered from a lack of precise control over the allocation and exercise of privileges within the Trusted Domain. Our contribution is the introduction of a model that allows for controlled access to the group, granular control over privileges, and guards against masquerading. Contin- ued good behavior is rewarded by an escalation of privileges, while requiring an increased commitment of resources. Bad behavior results in expulsion from the Trusted Domain. In colluding with malicious nodes, well behaved nodes risk losing privileges gained over time; collusion is thereby discouraged.

    We implement our solution on top of the Bouncer Toolkit, produced by Narasimha et al. [7], as a prototype peer to peer network. We make use of social models for trust from [], and rely on new cryptographic primitives from the field of Threshold Cryptography. We present the results of an experimental analysis of its performance for a number of thresholds, and present observations on a number of important performance and security improvements that can be made to the underlying toolkit.

  • jwhitney.pdf

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