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Fair and Efficient Helper-Aided MPC with Cheater Identification
eprint.iacr.orgpaper

Fair and Efficient Helper-Aided MPC with Cheater Identification

This paper introduces Alhena (synchronous) and Wasat (asynchronous), two helper-aided multi-party computation protocols that achieve "identifiable fairness": if an adversary aborts the protocol, no party gets the output and honest parties can identify at least one common cheater, closing a gap in prior fair-but-unaccountable helper-aided MPC schemes. The authors benchmark against state-of-the-art fair protocols Asterisk and Castor (both from Kamarkar et al., IEEE S&P 2024/2026), showing 4–12.5x and 2.5–5x online-phase speedups respectively, with online performance unaffected by active misbehavior.

TL;DR New helper-aided MPC protocols (Alhena, Wasat) add cheater identification to fairness guarantees while outperforming prior work (Asterisk, Castor) by 2.5–12.5x.
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Technologies named here

Techniques named here

  • Helper-aided MPC
  • Identifiable fairness
  • Dishonest-majority MPC
  • Abort attack / selective abort

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