Paper 2022/1369
Network-Agnostic Security Comes (Almost) for Free in DKG and MPC
Abstract
Distributed key generation (DKG) protocols are an essential building block for threshold cryptosystems. Many DKG protocols tolerate up to $t_s<n/2$ corruptions assuming a well-behaved synchronous network, but become insecure as soon as the network delay becomes unstable. On the other hand, solutions in the asynchronous model operate under arbitrary network conditions, but only tolerate $t_a<n/3$ corruptions, even when the network is well-behaved. In this work, we ask whether one can design a protocol that achieves security guarantees in either scenario. We show a complete characterization of network-agnostic DKG protocols, showing that the tight bound is $t_a+2t_s <n$. As a second contribution, we provide an optimized version of the network-agnostic MPC protocol by Blum, Liu-Zhang and Loss [CRYPTO'20] which improves over the communication complexity of their protocol by a linear factor. Moreover, using our DKG protocol, we can instantiate our MPC protocol in the plain PKI model, i.e., without the need to assume an expensive trusted setup. Our protocols incur the same communication complexity as state-of-the-art DKG and MPC protocols with optimal resilience in their respective purely synchronous and asynchronous settings, thereby showing that network-agnostic security comes (almost) for free.
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- A major revision of an IACR publication in CRYPTO 2023
- Contact author(s)
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renas bacho @ cispa de
daniel collins @ epfl ch
chen-da liuzhang @ ntt-research com
loss @ cispa de - History
- 2023-09-26: last of 7 revisions
- 2022-10-11: received
- See all versions
- Short URL
- https://ia.cr/2022/1369
- License
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CC BY
BibTeX
@misc{cryptoeprint:2022/1369, author = {Renas Bacho and Daniel Collins and Chen-Da Liu-Zhang and Julian Loss}, title = {Network-Agnostic Security Comes (Almost) for Free in {DKG} and {MPC}}, howpublished = {Cryptology {ePrint} Archive, Paper 2022/1369}, year = {2022}, url = {https://eprint.iacr.org/2022/1369} }