without sacri?cing the privacy and security of the individuals to whom the data correspond.

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.

The enormous success and diffusion that online social networks (OSNs) are encountering nowadays is vastly apparent. Users' social interactions now occur using online social media as communication channels; personal information and activities are easily exchanged both for recreational and business purposes in order to obtain social or economic advantages. In this scenario, OSNs are considered critical applications with respect to the security of users and their resources, for their characteristics alone: the large amount of personal information they manage, big economic upturn connected to...

Access control is one of the fundamental services that any Data Management System should provide. Its main goal is to protect data from unauthorized read and write operations. This is particularly crucial in today's open and interconnected world, where each kind of information can be easily made available to a huge user population, and where a damage or misuse of data may have unpredictable consequences that go beyond the boundaries where data reside or have been generated. This book provides an overview of the various developments in access control for data management systems....