SCS Faculty Candidate

  • Postdoctoral Researcher
  • Department of Computer and Information Science
  • University of Pennsylvania

Designing Systems for Skeptics

In modern distributed systems, users are increasingly being asked to rely on third parties who do not necessarily have their best interests in mind. For example, cloud hosted services offer a myriad of benefits, but they require users to trust the service provider with the confidentiality and integrity of their data and the correctness of the computations performed on it. The recent history of accidental and malicious data disclosures, misuse of users’ data, surreptitious censorship, and warrantless surveillance has shown that this trust is often misplaced. Moreover, non-technical mechanisms, such as laws and market incentives, have proved to be insufficient to mitigate these threats.

In this talk, I will present two implemented systems that enable their users to benefit from cloud deployment, but that are designed “for skeptics:” they provide users with guarantees that hold even if the service provider cannot be trusted. The first system, SPORC, makes it possible to build low-latency collaborative Web applications such as shared text editors, group calendars, and instant messaging applications with an untrusted provider. The provider only sees encrypted data and cannot deviate from correct execution without detection. And if the provider does misbehave, SPORC gives users a means to recover. Pantry, the second system, enables a user to outsource a general purpose computation to a potentially faulty provider and yet verify that the computation was performed correctly. Unlike prior efforts, Pantry allows verifiable computations to operate on remotely-stored data that the user does not possess, opening the way to a wide variety of uses such as MapReduce jobs and database queries.


Ariel Feldman is a postdoctoral researcher at the University of Pennsylvania whose research focuses on building systems that provide confidentiality, integrity, and correctness by design rather than solely through non-technical means, drawing on techniques from distributed systems, applied cryptography, and theory. He received his Ph.D. in computer science from Princeton University in 2012 under the supervision of Edward W. Felten and received an A.B. in computer science and in ethics and political philosophy from Brown University.

Faculty Host: Norman Sadeh

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