Paper 2023/1648
On-Chain Timestamps Are Accurate
Abstract
When Satoshi Nakamoto introduced Bitcoin, a central tenet was that the blockchain functions as a timestamping server. In the Ethereum era, smart contracts widely assume on-chain timestamps are mostly accurate. In this paper, we prove this is indeed the case, namely that recorded timestamps do not wildly deviate from real-world time, a property we call timeliness. Assuming a global clock, we prove that all popular mechanisms for constructing blockchains (proof-of-work, longest chain proof-of-stake, and quorum-based proof-of-stake) are timely under honest majority, but a synchronous network is a necessary condition. Next we show that all timely blockchains can be suitably modified, in a black-box fashion, such that all honest parties output exactly the same ledgers at the same round, achieving a property we call supersafety, which may be of independent interest. Conversely, we also show that supersafety implies (perfect) timeliness, completing the circle.
Metadata
- Available format(s)
-
PDF
- Category
- Applications
- Publication info
- Preprint.
- Keywords
- blockchaintimelinesssupersafetybitcoinouroborosstreamlet
- Contact author(s)
-
tzinas @ tzinas com
svatsan @ stanford edu
dionyziz @ gmail com - History
- 2023-10-26: approved
- 2023-10-24: received
- See all versions
- Short URL
- https://ia.cr/2023/1648
- License
-
CC BY-SA
BibTeX
@misc{cryptoeprint:2023/1648,
author = {Apostolos Tzinas and Srivatsan Sridhar and Dionysis Zindros},
title = {On-Chain Timestamps Are Accurate},
howpublished = {Cryptology {ePrint} Archive, Paper 2023/1648},
year = {2023},
url = {https://eprint.iacr.org/2023/1648}
}