Alexandra Henzinger
I am a postdoc at Stanford with Dan Boneh and an incoming Assistant Professor of Computer and Communication Sciences at EPFL, starting in Fall 2027. I completed my PhD in the PDOS and CSS groups at MIT, advised by Henry Corrigan-Gibbs. My email is ahenz@mit.edu.
My research builds computer systems that deliver privacy and security at scale. I work in computer security, systems, and cryptography. To learn more, see my thesis defense talk.
Selected research
- Tiptoe (SOSP 2023) is a private web search engine. Unlike Google or DuckDuckGo, the Tiptoe search engine only ever sees and answers encrypted search queries, ensuring that it learns—and leaks—nothing about what each user is searching for.
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SimplePIR
(USENIX Security 2023)
is a fast cryptographic private-information-retrieval (PIR) scheme,
with performance approaching hardware's memory bandwidth.
As of 2026, Apple is using SimplePIR in its Private Cloud Compute system. docs code application
- Nudge (USENIX Security 2026) is a cryptographically-private recommendations engine, performing large-scale data mining without revealing the data itself.
- Our work (Eurocrypt 2025) introduces a new approach to building homomorphic encryption, which allows for computing on encrypted data. press blog
- More recent work (Eurocrypt 2026) constructs two-server doubly efficient PIR that runs in sublinear time and quasilinear space—and that is concretely fast.
Preprints
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Catalytic Tree Evaluation from Matching Vectors
ITC 2026 Highlights talk
Publications
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Nudge: A Private Recommendations Engine
USENIX Security 2026
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Two-Server Private Information Retrieval in Sublinear Time and Quasilinear Space
EUROCRYPT 2026, ITC 2026 Highlights talk
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The Structured Generic-Group Model
EUROCRYPT 2026
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Somewhat Homomorphic Encryption from Linear Homomorphism and Sparse LPN
EUROCRYPT 2025Invited to the Journal of Cryptology
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Distributional Private Information Retrieval
USENIX Security 2025
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Private Web Search with Tiptoe
SOSP 2023
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One Server for the Price of Two: Simple and Fast Single-Server Private Information Retrieval
USENIX Security 2023
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Automated Mapping of Task-Based Programs onto Distributed and Heterogeneous Machines
SC 2023
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Single-Server Private Information Retrieval with Sublinear Amortized Time
EUROCRYPT 2022
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ILP-based Local Search for Graph Partitioning
SEA 2018 · ACM Journal of Experimental Algorithmics 2020
Talks
Private Recommendations with Nudge
- USENIX Security · Baltimore, MD · August 2026 · slides
Two-Server Private Information Retrieval in Sublinear Time and Quasilinear Space
- MIT CIS Seminar · Boston, MA · November 2025 · with Seyoon Ragavan · slides
Somewhat Homomorphic Encryption from Coding-Theoretic Cryptography
- ENSL/CWI/KCL/IRISA Joint Cryptography Seminar · virtual · November 2025
- Simons Institute · Berkeley, CA · June 2025
- FHE.org meetup · virtual · June 2025
- EUROCRYPT · Madrid, Spain · May 2025 · slides
- Texas Crypto Day · Austin, TX · April 2025
- MIT Cryptography and Security Day · Boston, MA · January 2025 · video
- Oberwolfach Workshop on Cryptography · Oberwolfach, Germany · January 2025
Private Web Search with Tiptoe
- UIUC Security and Privacy Seminar · virtual · February 2025
- Boston University · Boston, MA · October 2024
- EPFL Summer Research Institute · Lausanne, Switzerland · July 2024
- RSA Conference · San Francisco, CA · May 2024
- Real World Crypto · Toronto, CA · March 2024 · slides video
- Penn Security and Privacy Seminar · Philadelphia, PA · February 2024
- Brave Research · virtual · February 2024
- University of Michigan · virtual · January 2024
- Princeton Systems Lunch · Princeton, NJ · December 2023
- Duality Technologies · virtual · December 2023
- Cornell Systems Lunch · Ithaca, NY · December 2023
- Stanford Security Lunch · Stanford, CA · November 2023
- Berkeley Security Seminar · Berkeley, CA · November 2023
- MIT CIS Seminar · Cambridge, MA · November 2023
- SOSP · Koblenz, Germany · October 2023
- Brown University · Providence, RI · October 2023
- CRYPTO PPML · Santa Barbara, CA · August 2023 · video
Protecting our Privacy, one Search at a Time
- MIT Libraries · Cambridge, MA (virtual) · August 2023
- MIT CSAIL Symposium: AI Frontiers & Implications · Cambridge, MA · June 2023 · video
Simple and Fast Single-Server Private Information Retrieval
- USENIX Security · Anaheim, CA · August 2023 · slides video
- Privacy Engineering group, Amazon Web Services · virtual · April 2023
- Berkeley Security Seminar · Berkeley, CA · March 2023
- Penn Distributed Systems Lab Seminar · Philadelphia, PA · February 2023
- Cornell Security Seminar · New York, NY · November 2022
- Cloudflare Research · virtual · October 2022
- Google · New York, NY · October 2022
Single-Server Private Information Retrieval with Sublinear Amortized Time
- New York Crypto Day · New York, NY · January 2023
- CMU CyLab Crypto Seminar · Pittsburgh, PA · September 2022 · video
- University of Maryland · College Park, MD (virtual) · September 2022
- Simons Institute · Berkeley, CA · June 2022 · slides video
- Stanford Security Seminar · Stanford, CA · June 2022
- EUROCRYPT · Trondheim, Norway · May 2022 · slides video
- NYU · New York, NY (virtual) · May 2022
- Charles River Crypto Day · Boston, MA · April 2022 · video