Actually an anti-bitcoin entity could perform a 51% attack without buying too much equipment. If I were a government or other such entity and looking to perform a 51% attack I would look into opening up a bitcoin mining pool. They could just payout higher than average and miners would slowly begin moving over to that pool. If you are making y bitcoin per xxx hashrate and I start a pool offering y+20% bitcoin per xxx hashrate, there is no doubt people would start moving over.
With all the cloud-hashing schemes and other scams out there, most people wouldn't even question how is possible for such high payments. Others would suspect something, but most would not care as long as the payments kept flowing in.
So at roughly 144 blocks per day * 25 BTC reward * $300 = $1.08 million per day currently mined. So they offer extra 20% would only cost them ~$200,000 a day. Actually it would be quite a bit less since it would take time to build up a loyal following of miners and they would only need 51%. So only toward the end of the operation would they be paying out in excess of $100,000 a day, They could probably start the operation with just a few thousand a day as people first started to move over.
So the question would become how long until they could convince enough people to move over. If only 30-45 days, I think they could pull it off for around $2-3 million. Heck this is low enough amount where even a large company or high net-worth individual might try it on their own... Thoughts?
As people begin to migrate over, the community will see that this pool is gaining almost 51% of the hash rate. Then a shitstorm will ensue and that pool will lose those miners. Just look at what happened when Ghash.io almost had 50% of the mining power. They lost a lot of miners and the miners went to other pools to keep any one pool from getting 51%. The anti-bitcoin entity would have to get its own miners and mine by itself to get 51%. Also, if such an attack succeeded and discredited Bitcoin, then all of those Bitcoin they mined are worthless and tons of money was just wasted.
It is likely that they wouldn't succeed so hey, the government or whoever just made a lot of money that they can now use and maybe instead of attacking Bitcoin, they can adopt it and use it.
51% is not some magical number that as soon as someone gets 51% of the hash rate, they suddenly have full control over the blockchain. It doesn't work like that. What 51% means is that the miner has a majority of the hash rate, which means they have a higher probability of finding over half of the blocks. In reality, the entity would need 80, 90% or higher in order to successfully pull off such an attack. In the network's current state, that would be prohibitively expensive.
Yes, as I pointed out people would catch on of course. Did Ghash.io offer a 20% premium over other pools at that time?
My question was, would the 20% premium over other pools cause most people to not care and keep mining at the higher paying pool? If not 20% how about 25%, 50%. At some point I think greed would outweigh the concern for the network.
As far as the 51%, they could just as well get the 60% or 80% whatever would need. My main argument was to counter everyone thinking you would need to purchase a bunch of hardware and operate it to pull this off. I was simply suggesting an alternative where a few million dollars could be used against the community by bribing the miners over to a rogue pool.
Edit: I see after researching Ghash.io did indeed offer a premium at first. But they later removed it. So the questions still stands: Did the miners leave because of concern for the network or due to the removal of the promotional bonus? I am sure they lost some of each group, but I think the majority was due to the loss of the premium.
