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Yeah, they could do that, but what most of these claims ("X could easily profit Y by doing 50%+1 attack") miss, is that once that attack has been made, who'd tr

Yeah, they could do that, but what most of these claims ("X could easily profit Y by doing 50%+1 attack") miss, is that once that attack has been made, who'd trade anything with the currency that was attacked? Lets say nvidia does "conquer" Bitcoin and have all the bitcoins, who'd in the right mind would continue to buy/sell Bitcoins after that? The market for Bitcoin would collapse faster than nvidia could excitedly scream "PROFITS!" to their shareholders, making the whole attack unnecessary in the first place.

belltaco 5y ago
Can such an attack be done without detection?
- capableweb 5y ago
  No, the whole point of using a blockchain is to have a publicly verifiable ledger of all transactions. If anything goes wrong, there will be so many alarm bells ringing across the world that probably it'll be a hearable event for most people living in places that resembles modern civilization.
  - stouset 5y ago
    You can sell your cryptocurrency for real dollars before openly performing your 51% attack.
    - toolz 5y ago
      The idea that you could buy a real-world item worth half as much as the amount of ETH/BTC you would mine in an hour or two or 51% is simply unrealistic. ETH mining at 500TH (a solid chunk over 51% just for ease) would net you 300 ETH an hour...that's 1.1 million USD, which means you would have to be able to purchase millions of dollars worth of real world items that would be released to you within the time-frame of your attack (in this case an hour) to make this even approaching "worth it" from a risk/reward viewpoint and even that calculation is ignoring just how profitable they'd be just mining normally for the foreseeable future. No one is waiting for just an hour worth of confirmations for millions of dollars of real world goods exchanged for ETH.
      - rasz 5y ago
        Wouldnt 51% attack allow you to rewrite contracts?
        toolz 5y ago
        no, contracts are immutable, I'm unaware of any base-layer chain attacks that can affect contracts negatively (outside of contract level logic that may be vulnerable itself)
paulgb 5y ago
A 51% attack can only reverse a transaction anyway, it can’t arbitrarily take money from someone you haven’t transacted with. But they could get short exposure to btc/eth in the market, profit when it went down from the ensuing panic, and then sell the graphics cards to retail (there are other complications that make this unrealistic, of course.)
- Proven 5y ago
jcranmer 5y ago
Well, the history of actual 50% attacks on cryptocurrencies in the past few years seems to suggest that effect of a 50% attack on the value of the cryptocurrency is... pretty close to nil, actually. Admittedly, a successful attack on a major cryptocurrency like Bitcoin or Etherium is likely to have far different impact on cryptocurrency society than one on a minor cryptocurrency, but the ability of the community to twist every bad news into "this is good for Bitcoin" should not be underestimated.
sdenton4 5y ago
I suppose any of the Faang companies could sacrifice a data center for a day or two to do the same. Just crash the currency and get out, to eliminate proof of work currencies.
- capableweb 5y ago
  Again, why would they? They only stand to lose on it, so why do it in the first place?
  - sdenton4 5y ago
    NVIDIA would reduce demand, but for the FAANG companies it's a neutral proposition, aside from the cost of doing the work to crash the currency. And there's plenty of reasons to want to do so: Proof-of-work currencies are what make ransomware payments possible, and there's a large daily CO2 cost for proof of work currencies. The question is simply when is the cost of the externalities greater than the cost of acting?
    - trulyme 5y ago
      Am I missing something? Why would NVIDIA want to reduce demand for their graphic cards?
      - hnaccount_rng 5y ago
        There is actually a good case to make here. Nvidia currently is in the tough spot of a) not having the capacity to saturate the market and b) not being able to expand the production to match. B is because they don’t have enough confidence that the crypto people will be there as costumers in 5 years. And A is a problem, because their traditional user base (ie gamers) won’t match the spending, but will still get their fix (just not from Nvidia). And that breaks the strangle hold that they had a couple of years ago on that market. So short term: having the high prices paid by crypto people is nice. But it destroys their relationship to their old customer base. Depending on where the crypto market will be in 5, 10, 15 years, this can be the 5x of their market cap or the 0.2x

belltaco 5y ago

Can such an attack be done without detection?

capableweb 5y ago
No, the whole point of using a blockchain is to have a publicly verifiable ledger of all transactions. If anything goes wrong, there will be so many alarm bells ringing across the world that probably it'll be a hearable event for most people living in places that resembles modern civilization.
- stouset 5y ago
  You can sell your cryptocurrency for real dollars before openly performing your 51% attack.
  - toolz 5y ago
    The idea that you could buy a real-world item worth half as much as the amount of ETH/BTC you would mine in an hour or two or 51% is simply unrealistic. ETH mining at 500TH (a solid chunk over 51% just for ease) would net you 300 ETH an hour...that's 1.1 million USD, which means you would have to be able to purchase millions of dollars worth of real world items that would be released to you within the time-frame of your attack (in this case an hour) to make this even approaching "worth it" from a risk/reward viewpoint and even that calculation is ignoring just how profitable they'd be just mining normally for the foreseeable future. No one is waiting for just an hour worth of confirmations for millions of dollars of real world goods exchanged for ETH.
    - rasz 5y ago
      Wouldnt 51% attack allow you to rewrite contracts?
      - toolz 5y ago
        no, contracts are immutable, I'm unaware of any base-layer chain attacks that can affect contracts negatively (outside of contract level logic that may be vulnerable itself)

paulgb 5y ago

A 51% attack can only reverse a transaction anyway, it can’t arbitrarily take money from someone you haven’t transacted with. But they could get short exposure to btc/eth in the market, profit when it went down from the ensuing panic, and then sell the graphics cards to retail (there are other complications that make this unrealistic, of course.)

Proven 5y ago

jcranmer 5y ago

Well, the history of actual 50% attacks on cryptocurrencies in the past few years seems to suggest that effect of a 50% attack on the value of the cryptocurrency is... pretty close to nil, actually. Admittedly, a successful attack on a major cryptocurrency like Bitcoin or Etherium is likely to have far different impact on cryptocurrency society than one on a minor cryptocurrency, but the ability of the community to twist every bad news into "this is good for Bitcoin" should not be underestimated.

sdenton4 5y ago

I suppose any of the Faang companies could sacrifice a data center for a day or two to do the same. Just crash the currency and get out, to eliminate proof of work currencies.

capableweb 5y ago
Again, why would they? They only stand to lose on it, so why do it in the first place?
- sdenton4 5y ago
  NVIDIA would reduce demand, but for the FAANG companies it's a neutral proposition, aside from the cost of doing the work to crash the currency. And there's plenty of reasons to want to do so: Proof-of-work currencies are what make ransomware payments possible, and there's a large daily CO2 cost for proof of work currencies. The question is simply when is the cost of the externalities greater than the cost of acting?
  - trulyme 5y ago
    Am I missing something? Why would NVIDIA want to reduce demand for their graphic cards?
    - hnaccount_rng 5y ago
      There is actually a good case to make here. Nvidia currently is in the tough spot of a) not having the capacity to saturate the market and b) not being able to expand the production to match. B is because they don’t have enough confidence that the crypto people will be there as costumers in 5 years. And A is a problem, because their traditional user base (ie gamers) won’t match the spending, but will still get their fix (just not from Nvidia). And that breaks the strangle hold that they had a couple of years ago on that market. So short term: having the high prices paid by crypto people is nice. But it destroys their relationship to their old customer base. Depending on where the crypto market will be in 5, 10, 15 years, this can be the 5x of their market cap or the 0.2x