[Resource Topic] 2023/278: Actively Secure Half-Gates with Minimum Overhead under Duplex Networks

Welcome to the resource topic for 2023/278

Title:
Actively Secure Half-Gates with Minimum Overhead under Duplex Networks

Authors: Hongrui Cui, Xiao Wang, Kang Yang, Yu Yu

Abstract:

Actively secure two-party computation (2PC) is one of the canonical building blocks
in modern cryptography. One main goal for designing actively secure 2PC protocols is to reduce the communication overhead, compared to semi-honest 2PC protocols.
In this paper, we propose a new actively secure constant-round 2PC protocol with one-way communication of 2\kappa+5 bits per AND gate (for \kappa-bit computational
security and any statistical security), essentially matching the one-way communication of semi-honest half-gates protocol. This is achieved by two new techniques:

  1. The recent compression technique by Dittmer et al. (Crypto 2022) shows that a relaxed preprocessing is sufficient for authenticated garbling that does not reveal masked wire values to the garbler. We introduce a new form of authenticated bits and propose a new technique of generating authenticated AND triples to reduce the one-way communication of preprocessing from 5\rho+1 bits to 2 bits per AND gate for \rho-bit statistical security.

  2. Unfortunately, the above compressing technique is only compatible
    with a less compact authenticated garbled circuit of size 2\kappa+3\rho bits per AND gate.
    We designed a new authenticated garbling that does not use information
    theoretic MACs but rather dual execution without leakage to authenticate wire values in the circuit.
    This allows us to use a more compact half-gates based authenticated garbled circuit of size 2\kappa+1 bits per AND gate, and meanwhile keep compatible
    with the compression technique. Our new technique can achieve one-way communication of 2\kappa+5 bits per AND gate.

Our technique of yielding authenticated AND triples can also be used to optimize the two-way communication (i.e., the total communication) by combining it with the authenticated garbled circuits by Dittmer et al., which results in an actively secure 2PC protocol with two-way communication of 2\kappa+3\rho+4 bits per AND gate.

ePrint: https://eprint.iacr.org/2023/278

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