제가 알기로는 51%의 해시파워를 갖고 있으면 (아니 이것보다 적은 해시파워를 가져도 시도는 할 수 있지만 성공가능성이 아주 낮죠, 하지만 51% 해시파워를 갖고 있으면 100%로 성공합니다) 실제 돈 받을 사람이 1 컨펌이든 3 컨펌이든 6 컨펌이든 기다린다고 하더라도 51%의 해시파워를 가진 어태커가 그 사이에 수신자가 받은 블록보더 더 긴 블록을 만들어서 푸쉬하면 여전히 가능하고 수신자의 트랜잭션의 지워버릴 수가 있습니다.
https://en.bitcoin.it/wiki/Irreversible_Transactions
Majority attack
Also referred to as a 51% attack or >50% attack. If the attacker controls more than half of the network hashrate, the previous attack has a probability of 100% to succeed. Since the attacker can generate blocks faster than the rest of the network, he can simply persevere with his private fork until it becomes longer than the branch built by the honest network, from whatever disadvantage.
No amount of confirmations can prevent this attack; however, waiting for confirmations does increase the aggregate resource cost of performing the attack, which could potentially make it unprofitable or delay it long enough for the circumstances to change or slower-acting synchronization methods to kick in. Bitcoin's security model relies on no single coalition of miners controlling more than half the mining power. A miner with more than 50% hash power is incentived to reduce their mining power and reframe from attacking in order for their mining equipment and bitcoin income to retain it's value.
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이론적으로는 51% 어택이 가능하나, 경제적 동기가 없기 때문에 이론적으로 불가능합니다.
현실적으로 하지 않는다는 이야기시겠죠?