51% 공격
51% 공격은 단일 개체가 블록체인 채굴 능력의 절반 이상을 장악할 때 발생하는 공격입니다.
The feasibility of a 51% attack depends heavily on the total hash rate of the network. On a small, niche PoW chain with low total mining power, an attacker could potentially rent enough hash power (via services like NiceHash) to execute the attack for a few hours. On a major network like Bitcoin, the physical acquisition of enough ASICs (Application-Specific Integrated Circuits) and the necessary electricity would cost billions of dollars, making the attack financially irrational—the attacker would essentially destroy the value of the network they just invested billions in to control.
graph LR
Center["51% 공격"]:::main
Pre_consensus_mechanisms["consensus-mechanisms"]:::pre --> Center
click Pre_consensus_mechanisms "/terms/consensus-mechanisms"
Pre_proof_of_work["proof-of-work"]:::pre --> Center
click Pre_proof_of_work "/terms/proof-of-work"
Pre_proof_of_stake["proof-of-stake"]:::pre --> Center
click Pre_proof_of_stake "/terms/proof-of-stake"
Rel_double_spending["double-spending"]:::related -.-> Center
click Rel_double_spending "/terms/double-spending"
Rel_sybil_attack["sybil-attack"]:::related -.-> Center
click Rel_sybil_attack "/terms/sybil-attack"
Rel_hard_fork["hard-fork"]:::related -.-> Center
click Rel_hard_fork "/terms/hard-fork"
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🧒 5살도 이해할 수 있게 설명
반 친구들 중 절반 넘게 짜고서 거짓말을 하기로 하면, 그게 진짜처럼 받아들여지는 것과 같아요. 다수의 힘을 이용해 규칙을 어기는 거죠.
🤓 Expert Deep Dive
Technically, a 51% attack is an exploit of the Nakamoto Consensus 'Longest Chain Rule'. When an attacker controls >50% hashrate, they can generate a private version of the blockchain faster than the rest of the network combined. By keeping this fork secret and then 'releasing' it once it is longer than the public chain, the network is forced to follow the attacker's chain due to the rules of 'Chainwork'. This results in a 'Chain Reorganization' (reorg). The primary damage is the ability to 'Double-Spend' by broadcasting a transaction on the public chain, waiting for confirmation, then releasing the private chain where that transaction never happened.