Paper 2023/271

Swoosh: Practical Lattice-Based Non-Interactive Key Exchange

Phillip Gajland, Max Planck Institute for Security and Privacy, Ruhr University Bochum
Bor de Kock, Norwegian University of Science and Technology
Miguel Quaresma, Max Planck Institute for Security and Privacy
Giulio Malavolta, Max Planck Institute for Security and Privacy
Peter Schwabe, Max Planck Institute for Security and Privacy, Radboud University Nijmegen

The advent of quantum computers has generated a wave of interest for post-quantum cryptographic schemes, as a replacement for currently used cryptographic primitives. In this context, lattice-based cryptography has emerged as the leading paradigm to build post-quantum cryptography. However, all viable replacements of the classical Diffie-Hellman key exchange require additional rounds of interactions, thus failing to achieve all the benefits of this protocol. Although earlier work has shown that lattice-based Non-Interactive Key Exchange (NIKE) is theoretically possible, it has been considered too inefficient for real-life applications. In this work, we provide the first evidence against this folklore belief. We construct a practical lattice-based NIKE whose security is based on the standard module learning with errors (M-LWE) problem in the quantum random oracle model. Our scheme is obtained in two steps: (i) A passively-secure construction that achieves a strong notion of correctness, coupled with (ii) a generic compiler that turns any such scheme into an actively secure one. To substantiate our efficiency claim, we present an optimised implementation of our construction in Rust and Jasmin, demonstrating its applicability to real-world scenarios. For this we obtain public keys of approximately 220 KBs and the computation of shared keys takes than 12 million cycles on an Intel Skylake CPU at a post-quantum security level of more than 120 bits.

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Public-key cryptography
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phillip gajland @ mpi-sp org
bor dekock @ ntnu no
miguel quaresma @ mpi-sp org
giulio malavolta @ mpi-sp org
peter @ cryptojedi org
2023-02-27: approved
2023-02-23: received
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      author = {Phillip Gajland and Bor de Kock and Miguel Quaresma and Giulio Malavolta and Peter Schwabe},
      title = {Swoosh: Practical Lattice-Based Non-Interactive Key Exchange},
      howpublished = {Cryptology ePrint Archive, Paper 2023/271},
      year = {2023},
      note = {\url{}},
      url = {}
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