Paper 2025/880

Optimistic Asynchronous Dynamic-committee Proactive Secret Sharing

Bin Hu, Beihang University
Jianwei Liu, Beihang University
Zhenliang Lu, Nanyang Technological University
Qiang Tang, The University of Sydney
Zhuolun Xiang, Aptos Labs
Zongyang Zhang, Beihang University
Abstract

Dynamic-committee Proactive Secret Sharing (DPSS) has gained increased attention for its ability to dynamically update shareholder committees and refresh secret shares, even under adversaries that gradually corrupt all nodes. However, existing state-of-the-art asynchronous DPSS protocols suffer from significant message complexity and communication complexity, where denotes the security parameter and is the committee size. In this paper, under the trusted setup assumption, we propose the first asynchronous DPSS protocol with message complexity in all scenarios. Additionally, our protocol achieves communication complexity in the optimistic case, where all nodes are honest and the network is synchronous, and communication complexity in the worst case. Without a trusted setup, in the optimistic case, the message complexity is , and the communication complexity is . In the worst case, our protocol preserves state-of-the-art message and communication complexities, i.e., and , respectively. Besides, our protocol supports batch amortization and accommodates high thresholds. For committee sizes of 4 to 400, the estimated concrete communication cost of our DPSS is 19--100x (resp., 8--14x) smaller in the optimistic case (resp., worst case) compared to the state-of-the-art. Experiments in AWS show that our DPSS achieves a latency of 1.9--8 seconds for committee sizes from 4 to 64. Single-machine benchmarks reveal a (computational) runtime reduction of up to 44%.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Preprint.
Contact author(s)
hubin0205 @ buaa edu cn
liujianwei @ buaa edu cn
zhenliang lu @ ntu edu sg
qiang tang @ sydney edu au
xiangzhuolun @ gmail com
zongyangzhang @ buaa edu cn
History
2025-05-19: approved
2025-05-17: received
See all versions
Short URL
https://ia.cr/2025/880
License
Creative Commons Attribution-NonCommercial
CC BY-NC

BibTeX

@misc{cryptoeprint:2025/880,
      author = {Bin Hu and Jianwei Liu and Zhenliang Lu and Qiang Tang and Zhuolun Xiang and Zongyang Zhang},
      title = {Optimistic Asynchronous Dynamic-committee Proactive Secret Sharing},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/880},
      year = {2025},
      url = {https://eprint.iacr.org/2025/880}
}
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