Paper 2023/1326

Accio: Variable-Amount, Optimized-Unlinkable and NIZK-Free Off-Chain Payments via Hubs

Zhonghui Ge, Shanghai Jiao Tong University
Jiayuan Gu, Shanghai Jiao Tong University
Chenke Wang, Shanghai Jiao Tong University
Yu Long, Shanghai Jiao Tong University
Xian Xu, East China University of Science and Technology
Dawu Gu, Shanghai Jiao Tong University

Payment channel hubs (PCHs) serve as a promising solution to achieving quick off-chain payments between pairs of users. They work by using an untrusted tumbler to relay the payments between the payer and payee and enjoy the advantages of low cost and high scalability. However, the most recent privacy-preserving payment channel hub solution that supports variable payment amounts suffers from limited unlinkability, e.g., being vulnerable to the abort attack. Moreover, this solution utilizes non-interactive zero-knowledge proofs, which bring huge costs on both computation time and communication overhead. Therefore, how to design PCHs that support variable amount payments and unlinkability, but reduce the use of huge-cost cryptographic tools as much as possible, is significant for the large-scale practical applications of off-chain payments. In this paper, we propose Accio, a variable amount payment channel hub solution with optimized unlinkability, by deepening research on unlinkability and constructing a new cryptographic tool. We provide the detailed Accio protocol and formally prove its security and privacy under the Universally Composable framework. Our prototype demonstrates its feasibility and the evaluation shows that Accio outperforms the other state-of-the-art works in both communication and computation costs.

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Publication info
Published elsewhere. Minor revision. ACM CCS 2023
Payment Channel HubVariable AmountUnlinkabilityNIZK-free
Contact author(s)
zhonghui ge @ sjtu edu cn
sjtu_gjy @ sjtu edu cn
w_chenke @ sjtu edu cn
longyu @ sjtu edu cn
xuxian @ ecust edu cn
dwgu @ sjtu edu cn
2023-09-08: approved
2023-09-06: received
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      author = {Zhonghui Ge and Jiayuan Gu and Chenke Wang and Yu Long and Xian Xu and Dawu Gu},
      title = {Accio: Variable-Amount, Optimized-Unlinkable and {NIZK}-Free Off-Chain Payments via Hubs},
      howpublished = {Cryptology ePrint Archive, Paper 2023/1326},
      year = {2023},
      note = {\url{}},
      url = {}
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