O que é 51% attack?
An attack in which someone controlling a majority of hashrate reorganises recent blocks to reverse their own transactions.
A majority attacker can exclude transactions and reverse recent ones they made. They cannot steal coins from addresses they do not control, create coins outside the schedule, or change the rules — nodes reject invalid blocks regardless of work.
On Bitcoin the cost of acquiring and running that hashrate is enormous, and the attack destroys the value of the asset the attacker would be paid in.
A 51% attack does not let an attacker steal arbitrary coins or print new ones. Its scope is narrower than the phrase suggests.
Termos relacionados
Hashrate
The estimated total computing power searching for Bitcoin blocks, usually quoted in exahashes per second…
Como funcionaReorganisation (reorg)
When nodes switch to a different chain with more accumulated work, discarding one or more recently accepted…
EconomicsOrçamento de segurança
Total miner revenue — subsidy plus fees — which sets how expensive it would be to attack the chain.
RedeConsensus rules
The validity conditions every node enforces: issuance schedule, signature validity, block weight, and…
Esta definição faz parte do glossário da Bitcoin Logical. Para a explicação completa, comece por Aprender, ou veja os números ao vivo em O Sinal Bitcoin.