An attack on the source of randomness that determines which validator gets to produce the next block. By selectively withholding blocks or VRF outputs at the end of an epoch, an adversary tries to nudge the seed of the next epoch toward outcomes that elect its own pools more often.
Ouroboros Praos derives the per-epoch randomness from VRF outputs and bounds the adversary's grinding advantage through protocol parameters. Grinding does not require a stake majority: it trades computational effort for a small bias of the leader schedule, and becomes meaningfully feasible once an adversary controls roughly 20% of the stake. That residual sub-majority risk is why a VDF-based mitigation has been proposed in Ouroboros Phalanx. Genesis tightens related bounds for the dynamic-availability setting.
Explore next
- Proof-of-Stake AttacksThe set of known attack categories against proof-of-stake blockchains and how Cardano's Ouroboros family defends against each.View term
- Proof of StakeA consensus mechanism where validators are selected to create blocks based on the amount of cryptocurrency they hold and stake (commit) to the network.View term
- OuroborosThe family of proof-of-stake consensus protocols that power Cardano, designed with formal security proofs against the known attack catalogue against PoS chains.View term
- VRFA cryptographic function that produces a verifiably random output; Cardano uses it inside Ouroboros as a private per-slot lottery, letting each pool check whether it won the right to produce a block, fairly and unpredictably.View term