51% attack [English]
No definition in earlier IP projects. ITrust definition not yet developed.
- Bitcoin Developer Glossary 2017 (†791 s.v. "51 percent attack"): The ability of someone controlling a majority of network hash rate to revise transaction history and prevent new transactions from confirming.
- Bitcoin Group  (†846 s.v. "51% attack"): A condition in which more than half the computing power on a cryptocurrency network is controlled by a single miner or group of miners. That amount of power theoretically makes them the authority on the network. This means that every client on the network believes the attacker’s hashed transaction block. This gives them control over the network, including the power to: · Issue a transaction that conflicts with someone else’s. · Stop someone else’s transaction from being confirmed. · Spend the same coins multiple times. · Prevent other miners from mining valid blocks.
- BlockchainHub Glossary (†807 s.v. "51% attack"): A condition in which more than half the computing power of a cryptocurrency network is controlled by a single malicious miner or group of miners. If he controls 51% of the network that makes him the authority on the network, giving him the power to spend the same coins multiple times, issue transactions that conflict with someone else’s or stop someone else’s transaction from being confirmed.
- Scaling Bitcoin  (†845 s.v. "51% attack / Majority attack"): A majority attack (usually labeled 51% attack or >50% attack) is an attack on the network. This attack has a chance to work even if the merchant waits for some confirmations, but requires extremely high relative hashrate.