BU Sec Seminar: Alexandra Henzinger, PhD Student, MIT

Talk Title: Private web search with Tiptoe

Abstract: Our web search queries reveal sensitive information about us: where we are (“Hikes near Boston”), how we are feeling (“Causes of neck pain”), what we are doing (“How to find a lawyer”), and much more. Even if we use privacy-conscious search engines, such as DuckDuckGo, the search engine’s servers see our query strings in plaintext. As a result, search engines today accumulate a trove of sensitive data about us; this data is an attractive target for theft in a data breach, abuse by an authoritarian government, or sale to a third party.

This talk will present Tiptoe, a search engine that learns nothing about what its users are searching for. With Tiptoe, a client sends only the encryption of its search query to the search engine’s servers. The search engine then executes a cryptographic protocol to identify the web pages that best answer the user’s query—without ever decrypting the query, without learning what the user is searching for, and without learning what search results it is sending back. Tiptoe’s privacy guarantee is based on cryptography alone; it does not require any trusted hardware or non-colluding servers. The Tiptoe search engine answers these queries in the span of seconds: searching over a public web crawl (360 million pages) incurs 57 MiB of client-server communication and 2.7 seconds of client-perceived latency.

This talk is based on joint work with Emma Dauterman, Henry Corrigan-Gibbs, and Nickolai Zeldovich that appeared at SOSP 2023.

Bio: Alexandra Henzinger is a fifth-year Ph.D. student in the Parallel and Distributed Operating Systems (PDOS) group at MIT, advised by Henry Corrigan-Gibbs. Alexandra works on building computer systems that provably protect their users’ security and privacy. Much of her recent work has focused on private information retrieval, from designing cryptographic protocols to building a private search engine. Alexandra’s research is supported by an NSF GRFP fellowship and an MIT EECS Great Educators fellowship.

12:00 pm - 1:45pm (Lunch 12:00pm - 12:45pm, talk 12:45pm -1:45pm)

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