4 ms·

Every second, the amount of hashes computed on the Bitcoin network is equal to every grain of sand on earth, multiplied by 7. There isn't enough computing powe

by LAMike 7y ago

Every second, the amount of hashes computed on the Bitcoin network is equal to every grain of sand on earth, multiplied by 7. There isn't enough computing power available to 51% attack a chain that comes close to justify the $1 billion dollar "bounty" on this transaction.

ChrisClark 7y ago
It's quite possible, as long as the cost of the current ASICs out there is less than a billion. You can match the current world rate and secretly mine. It would be a combination of buying your own miners and renting hashrate, but mostly it would be renting. Maybe paying a big mine to do it for you. When I saw the initial math, they said 40 days. But that doesn't include the fact that as you buy hash power, it's price would go up. But to secretly mine for a week before reorganizing the chain would be very possible with this amount of money. I wonder if you could put in a checkpoint system. And if that could even be decentralized.
- lawn 7y ago
  I did some quick math a while ago on the cost to buy 51% [0]. When I did it the network hashrate was 44,000,000 TH/s and if you could buy enough S9i's to the same low price, it would cost you around $650 million. This is excluding any other infrastructure you'd need and of course the power you'd use to perform the attack. And since I did the calculations the hashrate has -doubled-, making it cost quite a bit more than a billion. Now maybe you can get off cheaper if you try to rent the hashrate. Around $18 million of BTC is mined per day, say you can get 50% for $10 million per day. So yes maybe you can do it for 40 days, if you want to risk a large part of that billion. And face the quite massive risk of tanking Bitcoin's value or facing devs who might launch a "protective hard fork". (This is assuming you -can- buy or rent enough hashrate, which is very uncertain). There are checkpoints in BTC, although they haven't been added since 2014. [0]: https://whycryptocurrencies.com/how_do_cryptocurrencies_work.html#economics-of-a-51%-attack https://whycryptocurrencies.com/how_do_cryptocurrencies_work...
  - oh_sigh 7y ago
    By the time you could source that many S9is, the hash rate would be higher, requiring you to source more, at which point maybe newer and better chips have come out, raising the hash rate yet again, making your investment worthless.
- bradstewart 7y ago
  Buy it wouldn't exactly be a secret if you're paying a big mine to do it, or if you purchased every available mining ASIC out there at once (and found enough electricity/cooling to run them all).
bduerst 7y ago
Only if the attack is from the outside, which is not a requirement. It's not mutually exclusive. The miners who control the bitcoin network are already centralized on a handful of organizations in China. If they colluded on this attack they would take over >51% of the network because, hey, they already own and operate most of that computing power you're eluding to. Edit: There is also no evidence that the price would plummet from this, and given the history of theft, scams, forks, etc. involving bitcoin that do not drastically affect the price, I don't think it would either.
- jimmaswell 7y ago
  Wouldn't Bitcoin lose a lot of value if such an attack happened?
  - bduerst 7y ago
    Doubtful. The bitcoin community would react how it usually reacts towards large thefts or scams: blame the victim. I.e. It's their fault for not understanding X, doing Y, or having Z security; in this case the fault being having that much BTC in one wallet and one transaction.
  - kabacha 7y ago
    Yup BTC would be dead no doubt.
  - sp332 7y ago
    No, because future attacks wouldn't get any easier. One successful attack is just one successful attack. If your transaction is not worth a billion dollars, you're safe.
    - jimmaswell 7y ago
      I'm pretty sure a lot of people would lose trust in the whole ecosystem from such a thing happening and/or not want to use it anymore.
- oh_sigh 7y ago
celticninja 7y ago
If the bad actor already exists on the network then it is possible. No new adversary is going to be able to procure enough mining equipment and get it running in a small enough time frame, however an existing miner doesnt need 51%, they only need 51% - their own hash power.

by LAMike 7y ago

ChrisClark 7y ago

It's quite possible, as long as the cost of the current ASICs out there is less than a billion. You can match the current world rate and secretly mine. It would be a combination of buying your own miners and renting hashrate, but mostly it would be renting. Maybe paying a big mine to do it for you. When I saw the initial math, they said 40 days. But that doesn't include the fact that as you buy hash power, it's price would go up. But to secretly mine for a week before reorganizing the chain would be very possible with this amount of money. I wonder if you could put in a checkpoint system. And if that could even be decentralized.

lawn 7y ago
I did some quick math a while ago on the cost to buy 51% [0]. When I did it the network hashrate was 44,000,000 TH/s and if you could buy enough S9i's to the same low price, it would cost you around $650 million. This is excluding any other infrastructure you'd need and of course the power you'd use to perform the attack. And since I did the calculations the hashrate has -doubled-, making it cost quite a bit more than a billion. Now maybe you can get off cheaper if you try to rent the hashrate. Around $18 million of BTC is mined per day, say you can get 50% for $10 million per day. So yes maybe you can do it for 40 days, if you want to risk a large part of that billion. And face the quite massive risk of tanking Bitcoin's value or facing devs who might launch a "protective hard fork". (This is assuming you -can- buy or rent enough hashrate, which is very uncertain). There are checkpoints in BTC, although they haven't been added since 2014. [0]: https://whycryptocurrencies.com/how_do_cryptocurrencies_work.html#economics-of-a-51%-attack https://whycryptocurrencies.com/how_do_cryptocurrencies_work...
- oh_sigh 7y ago
  By the time you could source that many S9is, the hash rate would be higher, requiring you to source more, at which point maybe newer and better chips have come out, raising the hash rate yet again, making your investment worthless.
bradstewart 7y ago
Buy it wouldn't exactly be a secret if you're paying a big mine to do it, or if you purchased every available mining ASIC out there at once (and found enough electricity/cooling to run them all).

bduerst 7y ago

Only if the attack is from the outside, which is not a requirement. It's not mutually exclusive. The miners who control the bitcoin network are already centralized on a handful of organizations in China. If they colluded on this attack they would take over >51% of the network because, hey, they already own and operate most of that computing power you're eluding to. Edit: There is also no evidence that the price would plummet from this, and given the history of theft, scams, forks, etc. involving bitcoin that do not drastically affect the price, I don't think it would either.

jimmaswell 7y ago
Wouldn't Bitcoin lose a lot of value if such an attack happened?
- bduerst 7y ago
  Doubtful. The bitcoin community would react how it usually reacts towards large thefts or scams: blame the victim. I.e. It's their fault for not understanding X, doing Y, or having Z security; in this case the fault being having that much BTC in one wallet and one transaction.
- kabacha 7y ago
  Yup BTC would be dead no doubt.
- sp332 7y ago
  No, because future attacks wouldn't get any easier. One successful attack is just one successful attack. If your transaction is not worth a billion dollars, you're safe.
  - jimmaswell 7y ago
    I'm pretty sure a lot of people would lose trust in the whole ecosystem from such a thing happening and/or not want to use it anymore.
oh_sigh 7y ago

celticninja 7y ago

If the bad actor already exists on the network then it is possible. No new adversary is going to be able to procure enough mining equipment and get it running in a small enough time frame, however an existing miner doesnt need 51%, they only need 51% - their own hash power.