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Fairness in the Wild: Secure Atomic Swap with External Incentives

Authors Hao Chung , Elaine Shi, Sri AravindaKrishnan Thyagarajan, Elisaweta Masserova

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Subject Classification

ACM Subject Classification
  • Theory of computation → Algorithmic mechanism design
  • Security and privacy
Keywords
  • Fair exchange
  • mechanism design
  • game-theoretic approaches to distributed computing
  • blockchains

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Abstract

Atomic swaps enable asset exchanges across blockchains without relying on trusted intermediaries, and are a key component of decentralized finance (DeFi) ecosystems. Recently, Rapidash (Financial Cryptography 2025) introduced an atomic swap protocol that remains incentive compatible under user-miner collusion, by ensuring that the honest strategy forms a coalition-resistant Nash equilibrium. However, Rapidash’s model assumes a closed system where players act solely based on internal protocol incentives. In practice, parties may be influenced by external incentives such as off-chain rewards or adversarial bribes, which can undermine such equilibrium guarantees.
In this work, we introduce a new game-theoretic notion, bounded maximin fairness, which ensures that honest participants remain protected against rational adversaries with arbitrary but bounded external incentives. We construct an atomic swap protocol that satisfies this notion, while preserving the equilibrium properties of prior work in the absence of external influence. As we show, our protocol is easy to implement and can be instantiated even in Bitcoin’s limited scripting language.

Cite As Get BibTex

Hao Chung, Elaine Shi, Sri AravindaKrishnan Thyagarajan, and Elisaweta Masserova. Fairness in the Wild: Secure Atomic Swap with External Incentives. In 40th International Symposium on Distributed Computing (DISC 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 397, pp. 23:1-23:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026) https://doi.org/10.4230/LIPIcs.DISC.2026.23

Author Details

Hao Chung
  • LayerZero Labs, Vancouver, Canada
Elaine Shi
  • Carnegie Mellon University, Pittsburgh, PA, USA
Sri AravindaKrishnan Thyagarajan
  • University of Sydney, Australia
Elisaweta Masserova
  • Carnegie Mellon University, Pittsburgh, PA, USA

Funding

  • Chung, Hao: Supported by NSF awards 2212746, 2044679, 1704788, a Packard Fellowship, a generous gift from the late Nikolai Mushegian, a gift from Google, and an ACE center grant from Algorand Foundation. Most of this work was conducted while Hao Chung was affiliated with Carnegie Mellon University.
  • Shi, Elaine: Supported by NSF awards 2212746, 2044679, 1704788, a Packard Fellowship, a generous gift from the late Nikolai Mushegian, a gift from Google, a gift from Cylab SBI, and an ACE center grant from Algorand Foundation.
  • Masserova, Elisaweta: Supported by NSF Grant 1801369, the CONIX Research Center, the Defense Advanced Research Projects Agency under contract FA8750-17-1-0059, a gift from Bosch, and the CBI postdoctoral fellowship.

References

  1. Oracle manipulation attacks are rising, creating a unique concern for defi, 2022. URL: https://www.chainalysis.com/blog/oracle-manipulation-attacks-rising/.
  2. Marcin Andrychowicz, Stefan Dziembowski, Daniel Malinowski, and Lukasz Mazurek. Secure Multiparty Computations on Bitcoin. In S&P, 2014. Google Scholar
  3. Iddo Bentov, Yan Ji, Fan Zhang, Lorenz Breidenbach, Philip Daian, and Ari Juels. Tesseract: Real-time cryptocurrency exchange using trusted hardware. In Proceedings of the 2019 ACM SIGSAC conference on computer and communications security, pages 1521-1538, 2019. URL: https://doi.org/10.1145/3319535.3363221.
  4. Iddo Bentov and Ranjit Kumaresan. How to Use Bitcoin to Design Fair Protocols. In CRYPTO, 2014. Google Scholar
  5. Manuel Blum. Coin flipping by telephone a protocol for solving impossible problems. SIGACT News, 15(1):23-27, January 1983. URL: https://doi.org/10.1145/1008908.1008911.
  6. Joseph Bonneau. Why buy when you can rent? - bribery attacks on bitcoin-style consensus. In FC Workshops, 2016. Google Scholar
  7. Arka Rai Choudhuri, Matthew Green, Abhishek Jain, Gabriel Kaptchuk, and Ian Miers. Fairness in an unfair world: Fair multiparty computation from public bulletin boards. In ACM CCS, 2017. Google Scholar
  8. Hao Chung, Elisaweta Masserova, Elaine Shi, and Sri Aravinda Krishnan Thyagarajan. Fairness in the wild: Secure atomic swap with external incentives. IACR Cryptol. ePrint Arch., 2025:1086, 2025. URL: https://eprint.iacr.org/2025/1086.
  9. Hao Chung, Elisaweta Masserova, Elaine Shi, and Sri AravindaKrishnan Thyagarajan. Rapidash: Foundations of side-contract-resilient fair exchange. Cryptology ePrint Archive, Paper 2022/1063, 2022. URL: https://eprint.iacr.org/2022/1063.
  10. Kai-Min Chung, T-H. Hubert Chan, Ting Wen, and Elaine Shi. Game-theoretic fairness meets multi-party protocols: The case of leader election. In CRYPTO, 2021. Google Scholar
  11. Kai-Min Chung, Yue Guo, Wei-Kai Lin, Rafael Pass, and Elaine Shi. Game theoretic notions of fairness in multi-party coin toss. In TCC, volume 11239, pages 563-596, 2018. URL: https://doi.org/10.1007/978-3-030-03807-6_21.
  12. Apoorvaa Deshpande and Maurice Herlihy. Privacy-preserving cross-chain atomic swaps. In International conference on financial cryptography and data security, pages 540-549. Springer, 2020. URL: https://doi.org/10.1007/978-3-030-54455-3_38.
  13. Stefan Dziembowski, Lisa Eckey, and Sebastian Faust. Fairswap: How to fairly exchange digital goods. In ACM CCS, 2018. Google Scholar
  14. Matheus V. X. Ferreira and David C. Parkes. Credible decentralized exchange design via verifiable sequencing rules. In STOC, pages 723-736, 2023. Google Scholar
  15. Maurice Herlihy. Atomic cross-chain swaps. In PODC, 2018. Google Scholar
  16. Ilan Komargodski, Shin'ichiro Matsuo, Elaine Shi, and Ke Wu. log*-round game-theoretically-fair leader election. In CRYPTO, 2022. Google Scholar
  17. Ahmed Kosba, Andrew Miller, Elaine Shi, Zikai Wen, and Charalampos Papamanthou. Hawk: The blockchain model of cryptography and privacy-preserving smart contracts. In S&P, 2016. Google Scholar
  18. Ranjit Kumaresan and Iddo Bentov. How to use bitcoin to incentivize correct computations. In Proceedings of the 2014 ACM SIGSAC Conference on Computer and Communications Security, CCS '14, pages 30-41. Association for Computing Machinery, 2014. URL: https://doi.org/10.1145/2660267.2660380.
  19. Giulio Malavolta, Pedro Moreno-Sanchez, Clara Schneidewind, Aniket Kate, and Matteo Maffei. Anonymous multi-hop locks for blockchain scalability and interoperability. In 26th Annual Network and Distributed System Security Symposium, NDSS 2019, San Diego, California, USA, February 24-27, 2019. The Internet Society, 2019. URL: https://www.ndss-symposium.org/ndss-paper/anonymous-multi-hop-locks-for-blockchain-scalability-and-interoperability/.
  20. Subhra Mazumdar. Towards faster settlement in htlc-based cross-chain atomic swaps. In 2022 IEEE 4th international conference on trust, privacy and security in intelligent systems, and applications (TPS-ISA), pages 295-304. IEEE, 2022. URL: https://doi.org/10.1109/TPS-ISA56441.2022.00043.
  21. Patrick McCorry, Alexander Hicks, and Sarah Meiklejohn. Smart contracts for bribing miners. In FC Workshops, 2018. Google Scholar
  22. Andrew Miller and Iddo Bentov. Zero-collateral lotteries in bitcoin and ethereum. In EuroS&P Workshops, 2017. Google Scholar
  23. Mahdi H. Miraz and David C. Donald. Atomic cross-chain swaps: Development, trajectory and potential of non-monetary digital token swap facilities. In AETiC, 2019. Google Scholar
  24. Tejaswi Nadahalli, Majid Khabbazian, and Roger Wattenhofer. Grief-free atomic swaps. In 2022 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), pages 1-9. IEEE, 2022. URL: https://doi.org/10.1109/ICBC54727.2022.9805490.
  25. Henning Pagnia and Felix C. Gartner. On the impossibility of fair exchange without a trusted third party. Technical report, TU Darmstadt, Germany, 1999. Google Scholar
  26. Rafael Pass and Elaine Shi. Fruitchains: A fair blockchain. In PODC, 2017. Google Scholar
  27. Kirti Singh, Vinay J Ribeiro, and Susmita Mandal. 4-swap: Achieving grief-free and bribery-safe atomic swaps using four transactions. In 7th Conference on Advances in Financial Technologies (AFT 2025), pages 32:1-32:22. Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2025. URL: https://doi.org/10.4230/LIPIcs.AFT.2025.32.
  28. Sri Aravinda Krishnan Thyagarajan, Pratik Soni, and Ke Wu. Game-theoretically fair distributed sampling. In CRYPTO (8), volume 14927 of Lecture Notes in Computer Science, pages 207-239. Springer, 2024. URL: https://doi.org/10.1007/978-3-031-68397-8_7.
  29. Itay Tsabary, Matan Yechieli, Alex Manuskin, and Ittay Eyal. MAD-HTLC: because HTLC is crazy-cheap to attack. In S&P, 2021. Google Scholar
  30. Ron van der Meyden. On the specification and verification of atomic swap smart contracts. In IEEE ICBC, 2019. Google Scholar
  31. Sarisht Wadhwa, Jannis Stoeter, Fan Zhang, and Kartik Nayak. He-htlc: Revisiting incentives in htlc. Cryptology ePrint Archive, Paper 2022/546, 2022. URL: https://doi.org/10.14722/ndss.2023.24775.
  32. Fredrik Winzer, Benjamin Herd, and Sebastian Faust. Temporary censorship attacks in the presence of rational miners. In IEEE European Symposium on Security and Privacy Workshops, 2019. Google Scholar
  33. Ke Wu, Gilad Asharov, and Elaine Shi. A complete characterization of game-theoretically fair, multi-party coin toss. In Eurocrypt, 2022. Google Scholar
  34. Yingjie Xue and Maurice Herlihy. Hedging against sore loser attacks in cross-chain transactions. In Proceedings of the 2021 ACM Symposium on Principles of Distributed Computing, pages 155-164, 2021. URL: https://doi.org/10.1145/3465084.3467904.
  35. Victor Zakhary, Divy Agrawal, and Amr El Abbadi. Atomic commitment across blockchains. Proc. VLDB Endow., 13(9):1319-1331, 2020. URL: https://doi.org/10.14778/3397230.3397231.
  36. Jean-Yves Zie, Jean-Christophe Deneuville, Jeremy Briffaut, and Benjamin Nguyen. Extending atomic cross-chain swaps. In Data Privacy Management, Cryptocurrencies and Blockchain Technology, 2019. Google Scholar
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