ZLB: A Blockchain to Tolerate Colluding Majorities
Alejandro Ranchal-Pedrosa, Vincent Gramoli

TL;DR
ZLB introduces a novel blockchain protocol capable of tolerating majority adversaries by combining accountable Byzantine agreement with transient disagreement tolerance, outperforming existing systems in speed and fault tolerance.
Contribution
It presents the first blockchain that can tolerate more than half of the system being malicious, leveraging recent theoretical advances to exclude deceitful replicas.
Findings
ZLB tolerates >50% adversarial control.
ZLB outperforms HotStuff in geo-distributed settings.
ZLB is nearly as fast as Red Belly Blockchain.
Abstract
In the general setting, consensus cannot be solved if an adversary controls a third of the system. Yet, blockchain participants typically reach consensus "eventually" despite an adversary controlling a minority of the system. Exceeding this cap is made possible by tolerating transient disagreements, where distinct participants select distinct blocks for the same index, before eventually agreeing to select the same block. Until now, no blockchain could tolerate an attacker controlling a majority of the system. In this paper, we present Zero-Loss Blockchain (ZLB), the first blockchain that tolerates an adversary controlling more than half of the system. ZLB is an open blockchain that combines recent theoretical advances in accountable Byzantine agreement to exclude undeniably deceitful replicas. progressively reduces the portion of deceitful replicas below ,…
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Taxonomy
TopicsBlockchain Technology Applications and Security · Privacy-Preserving Technologies in Data
