CAREER: Tools for building online services that hide metadata

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Online services track users and analyze their behavior to improve their products and monetize their services. Despite the benefits of collecting user information, data breaches and insider attacks have disastrous consequences. For example, the Ashley Madison breach highlights the danger of a leaked social graph (and what it implies about users’ relationships). Indeed, metadata (who, what, when, etc.) can be sensitive, but building services that are oblivious to certain information (e.g., which movies users watch, which messages are “liked”, or the social graph) poses significant technical and financial challenges. This project takes a provider-centric view to hiding metadata and sees companies not as adversaries, but as partners committed to safeguarding users’ information, provided that the necessary mechanisms are reasonable in terms of costs, features, and assumptions. Grounded by the needs of companies, this project designs algorithms, tools, and infrastructure to help services continue to work without accessing or collecting certain metadata (e.g., the social graph), limiting the harm of data breaches and insider attacks.This project improves widely applicable cryptographic primitives by making them more efficient; extends them with access control and accountability features so privacy is not at odds with functionality; supports private user feedback necessary to improve services (e.g., train spam filters); and makes the release of source code optional. This project also designs the first decentralized and verifiable ad exchange platform that allows users to receive targeted ads without violating their privacy. This platform will supplement other revenue sources to ensure the sustainability of metadata-private online services. Finally, the topics of this project cover critical and timely social issues such as privacy, fairness, and their impact on the financial stability of businesses. These concepts will be transitioned to the classroom through a new in-depth capstone course, yearly workshops, and dedicated chapters in existing systems and security courses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.