Paper 2026/1252

HedgeSwap: Universal Hedged Atomic Swaps Against Griefing Attacks

Ying-Teng Chen, Monash University

Shujie Cui, Monash University

Tsz Hon Yuen, Monash University

Joseph K. Liu, Monash University

Jiangshan Yu, The University of Sydney

Abstract

Universal atomic swaps [Oakland'22] replace hashed timelock contracts with adaptor signatures and verifiable timed dlogs, enabling secure cross-chain cryptocurrency exchanges that only require basic signature verification from the underlying blockchains. However, existing universal swap protocols remain vulnerable to griefing attacks, where a deviating party aborts the swap to lock a compliant party's assets for a long period. A natural approach is to lift existing contract-based solutions to the universal setting, but we identify that this straightforward solution faces two key challenges: (i) timeout race attacks, first identified in PipeSwap [Oakland'25], which arises from the absence of an upper bound on the transaction validity; (ii) a timeout overlap dilemma, which results from multiple overlapping refund periods. In this paper, we propose HedgeSwap, a universal hedged atomic swap protocol against griefing attacks, which compensates a compliant party with a premium if its asset is locked but not redeemed. To mitigate the timeout race attacks and timeout overlap dilemma, HedgeSwap eliminates the premium timeout and instead relies on a hard relation to refund the premium. For high-value asset swaps where the parties acceptable premium ranges do not overlap, we further propose a round-based HedgeSwap that utilizes a premium migration mechanism to solve these two timeout challenges, where parties iteratively increase the premium until the lock-up risk premium acceptable to both. Our experimental results show that our HedgeSwap can complete in under 0.5 seconds, and round-based HedgeSwap completes in under 1.3 seconds for a five-round setting, while HedgeSwap reduces gas cost by 2.69X compared to existing contract-based solutions.

@misc{cryptoeprint:2026/1252,
      author = {Dongkun Hou and Ying-Teng Chen and Shujie Cui and Tsz Hon Yuen and Joseph K. Liu and Jiangshan Yu},
      title = {{HedgeSwap}: Universal Hedged Atomic Swaps Against Griefing Attacks},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/1252},
      year = {2026},
      url = {https://eprint.iacr.org/2026/1252}
}