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Laconic Branching Programs from the Diffie-Hellman Assumption

Authors:
Sanjam Garg , NTT Research and UC Berkeley
Mohammad Hajiabadi , University of Waterloo
Peihan Miao , Brown University
Alice Murphy , University of Waterloo
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Presentation: Slides
Conference: PKC 2024
Abstract: Laconic cryptography enables secure two-party computation (2PC) on unbalanced inputs with asymptotically-optimal communication in just two rounds of communication. In particular, the receiver (who sends the first-round message) holds a long input and the sender (who sends the second-round message) holds a short input, and the size of their communication to securely compute a function on their joint inputs only grows with the size of the sender's input and is independent of the receiver's input size. The work on laconic oblivious transfer (OT) [Cho et al. CRYPTO 2017] and laconic private set intersection (PSI) [Alamati et al. TCC 2021] shows how to achieve secure laconic computation for OT and PSI from the Diffie-Hellman assumption. In this work, we push the limits further and achieve laconic branching programs from the Diffie-Hellman assumption. In particular, the receiver holds a large branching program $P$ and the sender holds a short input $x$. We present a two-round 2PC protocol that allows the receiver to learn $x$ iff $P(x) =1$, and nothing else. The communication only grows with the size of $x$ and the depth of $P$, and does not further depend on the size of $P$.
BibTeX
@inproceedings{pkc-2024-33754,
  title={Laconic Branching Programs from the Diffie-Hellman Assumption},
  publisher={Springer-Verlag},
  author={Sanjam Garg and Mohammad Hajiabadi and Peihan Miao and Alice Murphy},
  year=2024
}