I.A. Emerging personal, social, and urban sensing applications Application context inevitably drives the architecture design choices and the definition of services needed in a network. Over the past decade, the emergence of unanticipated applications of the Internet, such as peer-to-peer file sharing, networked gaming, podcasting, and voice telephony, has contributed to a pressing need to rethink the core Internet infrastructure and its accompanying architectural choices. To truly lay a foundation for tomorrow’s infrastructure, however, requires going beyond simply reacting to applications that have already emerged, to proactively considering the architectural implications of new classes of applications. A key area in this regard involves embedded sensing technology, presently poised to moved beyond scientific, engineering, and industrial domains into broader and more diverse citizen-initiated sensing in personal, social and urban ones. Today, applications are emerging which draw on sensed information about people, objects, and physical spaces. These applications enable new kinds of social exchange: By collecting, processing, sharing, and visualizing this information, they can offer us new and unexpected views of our communities. To achieve their potential, these applications require fundamentally new algorithms and software mechanisms, because physical inputs now become critical. The research

Security is at once a technical property of a system and a socio-economic property of the environment in which it operates. The former property—focused on real or potential abuse resulting from unintended design or implementation vulnerabilities—encompasses the vast majority of security research and practice. Indeed, the very term “trustworthy system ” implicitly encodes the notion that security is a distinct and comprehensive property of the computing artifacts we use: secure against all adversaries and user failings. But history has shown that a perspective solely focused on technical considerations becomes mired in a relentless arms race. More importantly, this perspective misses an entire half of the problem space: the human element. Fundamentally, we care about security only because adversaries are motivated to attack us and because users prove susceptible to being victimized. Our proposal squarely focuses on addressing this other half of the problem space. We hold that while security is a phenomenon mediated by the technical workings of computers and networks, it is ultimately a conflict driven by economic and social issues which merit a commensurate level of scrutiny. Security is a game among actors: adversaries, defenders, and users. Together their behavior defines the shape of the threats we face, how they evolve over time, and, we argue, how they can best be addressed. A Socio-Economic Motivation. The need to address the social and economic elements of security has