How proof of stake secures a blockchain
Proof of stake secures a chain by making validators risk locked coins they lose if they cheat, then slashing misbehavior and finalizing by vote.
Vahe HakobyanEditor-in-chief
Updated Oct 6, 20263 min readFact-checked
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Proof of stake is one family of consensus mechanisms, the rules a blockchain uses to agree on one history of transactions. It gives validators influence based on how much of the network's coin they have locked up, not on computing power.
What is proof of stake in simple terms?
Proof of stake requires validators to lock up something valuable in the network, and the protocol can take that value away if they cheat. A validator suggests new blocks, checks other validators' work, and confirms the correct chain. The locked coins are the stake, and they are what an attacker has to overcome.
How does proof of stake secure a chain step by step?
The protocol divides time into short slots; each slot can hold at most one block and can be empty. One validator is randomly chosen to propose a block, and a committee of validators votes on it.
- 1Lock up the stakeOn Ethereum, a validator deposits ETH into a smart contract before joining; other proof-of-stake networks differ.
- 2Get picked at randomOne proposer is picked per slot, with odds weighted by stake, so the largest holder does not decide the order.
- 3Check the proposed blockOther validators re-execute the transactions to check them, then send an attestation in favor of the block.
- 4Lose stake for cheatingSlashing takes away part of a validator's stake and forces it out of the network for clear misbehavior, such as signing conflicting blocks.
- 5Reach finalityWhen a two-thirds supermajority of staked value agrees, those blocks cannot change without a large amount of ETH being burned.
How is proof of stake different from proof of work?
Both systems make cheating expensive, but the attacker pays in a different currency. Proof of work demands computing power and electricity; proof of stake demands the network's coins, held where the protocol can take them.
- Resource: proof of work spends computing power; proof of stake risks coins.
- Attack cost: an attacker needs most of the staked coins, not mining hardware.
- Energy: validators run ordinary machines, so electricity use is much lower.
Frequently asked questions
You usually keep ownership, but the coins join that validator's stake, and the protocol can take part of it away if the validator misbehaves.
Ethereum sets a fixed deposit of ETH for each validator, and staking pools let smaller holders combine funds to reach it.
Yes. Staking avoids mining's computational cost, but the low energy use is not what keeps the chain secure.
Validators use little computing power, so they could be tempted to vote for every competing fork, which could allow double-spending. Slashing makes that gamble expensive.
