International Association for Cryptologic Research

International Association
for Cryptologic Research


Two-Round Concurrent 2PC from Sub-Exponential LWE

Behzad Abdolmaleki , University of Sheffield, UK
Saikrishna Badrinarayanan , LinkedIn, USA
Rex Fernando , Carnegie Mellon University, USA
Giulio Malavolta , Max Planck Institute for Security and Privacy, Germany and Bocconi University, Italy
Ahmadreza Rahimi , Max Planck Institute for Security and Privacy, Germany
Amit Sahai , UCLA, Los Angeles, USA
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Presentation: Slides
Conference: ASIACRYPT 2023
Abstract: Secure computation is a cornerstone of modern cryptography and a rich body of research is devoted to understanding its round complexity. In this work, we consider two-party computation (2PC) protocols (where both parties receive output) that remain secure in the realistic setting where many instances of the protocol are executed in parallel (concurrent security). We obtain a two-round concurrent-secure 2PC protocol based on a single, standard, post-quantum assumption: The subexponential hardness of the learning-with-errors (LWE) problem. Our protocol is in the plain model, i.e., it has no trusted setup, and it is secure in the super-polynomial simulation framework of Pass (EUROCRYPT 2003). Since two rounds are minimal for (concurrent) 2PC, this work resolves the round complexity of concurrent 2PC from standard assumptions. As immediate applications, our work establishes feasibility results for interesting cryptographic primitives such as the first two-round password authentication key exchange (PAKE) protocol in the plain model and the first two-round concurrent secure computation protocol for quantum circuits (2PQC).
  title={Two-Round Concurrent 2PC from Sub-Exponential LWE},
  author={Behzad Abdolmaleki and Saikrishna Badrinarayanan and Rex Fernando and Giulio Malavolta and Ahmadreza Rahimi and Amit Sahai},