This book constitutes the refereed proceedings of the Third IFIP WG 11.11 International Conference, IFIPTM 2009, held in West Lafayette, IN, USA, in June 2009. The 17 revised full papers presented together with one invited paper and 5 demo descriptions were carefully reviewed and selected from 44 submissions. The papers are organized in topical sections on social aspects and usability, trust reasoning and processing, data security, enhancements to subjective logic, information sharing, risk assessment, and simulation of trust and reputation systems.

Social Aspects and Usability.- Spiral of Hatred: Social Effects in Buyer-Seller Cross-Comments Left on Internet Auctions.- Graphical Passwords as Browser Extension: Implementation and Usability Study.- Trust Reasoning and Processing.- Trust-Enhanced Recommender Systems for Efficient On-Line Collaboration.- Towards Understanding the Requirements and Limitations of Reputation-Based Systems.- Elimination of Subjectivity from Trust Recommendation.- Data Security.- Security in Wiki-Style Authoring Systems.- On Usage Control in Data Grids.- Detection and Prevention of Insider Threats in Database Driven Web Services.- Enhancements to Subjective Logic.- Inferring Trust Based on Similarity with TILLIT.- Analogical Trust Reasoning.- Information Sharing.- TIUPAM: A Framework for Trustworthiness-Centric Information Sharing.- TrustBuilder2: A Reconfigurable Framework for Trust Negotiation.- A Relational Wrapper for RDF Reification.- Risk Assessment.- Employing Key Indicators to Provide a Dynamic Risk Picture with a Notion of Confidence.- A Risk Based Approach to Limit the Effects of Covert Channels for Internet Sensor Data Aggregators for Sensor Privacy.- Simulation of Trust and Reputation Systems.- An Experimental Testbed for Evaluation of Trust and Reputation Systems.- Evaluating the STORE Reputation System in Multi-Agent Simulations.- Comparison of the Beta and the Hidden Markov Models of Trust in Dynamic Environments.- Demonstration Abstracts.- WRS: The Wikipedia Recommender System.- Distributed Systems Security Governance, a SOA Based Approach.- Security and Trust Management for Virtual Organisations: GridTrust Approach.- Common Capabilities for Trust and Security in Service Oriented Infrastructures.- A Virtual Hosting Environment for Distributed Online Gaming.