A 51% attack is a type of cyber attack that occurs when a group of miners or malicious actors control more than 50% of the computing power on a blockchain network. This gives them the ability to manipulate the network in a number of ways, including:
- Double spending: The attackers can spend the same cryptocurrency multiple times, essentially creating new money out of thin air.
- Reversing transactions: The attackers can reverse transactions that have already been verified and recorded on the blockchain.
- Blocking transactions: The attackers can block new transactions from being added to the blockchain, effectively shutting down the network.
- Changing the blockchain’s history: The attackers can change the history of the blockchain, including altering the transaction record and altering the balance of users’ accounts.
A 51% attack is a major concern for blockchain networks, as it can lead to a loss of trust in the network and undermine the integrity of the blockchain. To prevent a 51% attack, blockchain networks rely on decentralization and a large number of miners spread across a wide geographic area. This makes it difficult for any one group to gain control of a significant portion of the network’s computing power.