Post
Topic
Board Bitcoin Technical Support
Merits 3 from 2 users
Re: Question on 51% attack
by
bones261
on 23/12/2018, 03:19:22 UTC
⭐ Merited by logfiles (2) ,Bitcoinnation (1)
     To sum it up, if someone has more than 51% of the mining power, they can send coins to someone and receive goods/services/coins/fiat after getting enough confirmations. In the mean time, they can be working on an alternate chain and not release it to the network. On the alternate chain, the coins either remain unspent or are sent to someone else. Since the attacker has more hash than the rest of the network, eventually his alternate chain will be the chain with the most work. The attacker then releases their alternate chain, and the network switches to their chain because it has the most work. The original transaction disappears from the network. The attacker gets the goods/services/coins/fiat and the victim now has nothing.
     On the bitcoin network, this kind of attack is very expensive to implement. The risk the attacker takes is that it would probably make the market value of BTC or whatever coin he is attacking much less. One could argue that the attacker could make a big short sell on the market to actually profit from this. However, the cost to do this is so prohibitively high,(for BTC at least) that I don't think the markets are currently liquid enough to actually guarantee a profit with this strategy.