## CryptoDB

### Paper: Order-Fairness for Byzantine Consensus

Authors: Mahimna Kelkar , Cornell Tech, Cornell University, IC3 Fan Zhang , Cornell Tech, Cornell University, IC3 Steven Goldfeder , Cornell Tech, Cornell University, IC3 Ari Juels , Cornell Tech, Cornell University, IC3 DOI: 10.1007/978-3-030-56877-1_16 (login may be required) Search ePrint Search Google Slides CRYPTO 2020 Decades of research in both cryptography and distributed systems has extensively studied the problem of state machine replication, also known as Byzantine consensus. A consensus protocol must usually satisfy two properties: {\em consistency} and {\em liveness}. These properties ensure that honest participating nodes agree on the same log and dictate when fresh transactions get added. They fail, however, to ensure against adversarial manipulation of the actual {\em ordering} of transactions in the log. Indeed, in leader-based protocols (almost all protocols used today), malicious leaders can directly choose the final transaction ordering. To rectify this problem, we propose a third consensus property: {\em transaction order-fairness}. We initiate the first formal investigation of order-fairness and explain its fundamental importance. We also provide several natural definitions for order-fairness and analyze the assumptions necessary to realize them. We also propose a new class of consensus protocols called Aequitas. Aequitas protocols are the first to achieve order-fairness in addition to consistency and liveness. They can be realized in a black-box way using existing broadcast and agreement primitives (or indeed using any consensus protocol), and work in both synchronous and asynchronous network models.
##### BibTeX
@inproceedings{crypto-2020-30486,
title={Order-Fairness for Byzantine Consensus},
publisher={Springer-Verlag},
doi={10.1007/978-3-030-56877-1_16},
author={Mahimna Kelkar and Fan Zhang and Steven Goldfeder and Ari Juels},
year=2020
}