Paper 2020/661 Original: eprint.iacr.org/2020/661 ↗
Tight Consistency Bounds for Bitcoin
Abstract
We establish the optimal security threshold for the Bitcoin protocol in terms of adversarial hashing power, honest hashing power, and network delays. Specifically, we prove that the protocol is secure if $$r_a < \frac{1}{\Delta + 1/r_h}\; ,$$ where $r_h$ is the expected number of honest proof-of-work successes in unit time, $r_a$ is the expected number of adversarial successes, and no message is delayed by more than $\Delta$ time units. In this regime, the protocol guarantees consistency and liveness with exponentially decaying failure probabilities. Outside this region, the simple private chain attack prevents consensus. Our analysis immediately applies to any Nakamoto-style proof-of-work protocol; we also present the adaptations needed to apply it in the proof-of-stake setting, establishing a similar threshold there.
Metadata
- Available format(s)
PDF- Category
- Applications
- Publication info
- Preprint.
- History
- 2020-11-11: last updated
- 2020-06-03: published
- Short URL
- https://ia.cr/2020/661
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2020/661,
author = {Peter Gaži and Aggelos Kiayias and Alexander Russell},
title = {Tight Consistency Bounds for Bitcoin},
howpublished = {Cryptology {ePrint} Archive, Paper 2020/661},
year = {2020},
url = {https://eprint.iacr.org/2020/661}
}