5 ms·

In theory yes, but in practice it's rather infeasible to do 51% attacks IRL --- the main constraint is the people not the math. A 51% attack mainly lets you do

In theory yes, but in practice it's rather infeasible to do 51% attacks IRL --- the main constraint is the people not the math. A 51% attack mainly lets you double spend, so you have to: (1) get a lot of coins and spend them on something (2) start mining a fork where that spending didn't happen (but other real transactions continue to happen) --- your hash power will now need to be dedicated to this new fork at the exclusion of the old "real" fork since all future hashes will diverge (3) wait until the thing you paid for with coins can no longer be "taken back", all while continuing efforts on the alternate fork (4) do the 51% attack to swap out the old "real" fork with your new fork where you never bought the thing, thus keeping the thing _and_ the coins you spent on them (5) all this needs to be balanced with the opportunity cost had you just continued mining on the real chain... Such an attack would trigger immediate attention since at (2) the main chain would suddenly see a drop in contributions. Also realistically most things you can purchase with coins (like fiat or other goods/services) can be relatively easily "taken back" unless a considerable amount of time is spent to launder them --- say if you "buy" a car with crypto and reverse the transaction, what you've really done is just stolen a car with a lot of extra steps... Which means your only real viable path is to redeem for some other cryptocurrency... Now given that a big attack just happened on the largest market cap crypto, there's a pretty good chance the other coins are going to take a hit and exchanges might even temporarily limit activities while this situation is "investigated", greatly reducing what you can actually do at the end of the day. This kind of thing is more reasonable on the smaller market cap "meme" coins where you can just exchange them for for a mass-market crypto.

roofwellhams 6y ago
What if this drop in hash is to use on the 2nd chain?
- Thorrez 6y ago
  Well we have a good explanation of the drop: the power outages. Also with 25% hash power you're going to have a hard time doing a 51% attack.
  - roofwellhams 6y ago
    Let's say I'm a bad actor in us. I hear about this event in China and I start to do the 2nd chain. You'll think that China region was doing that 25% but maybe they were only doing 1% and I did the other 24%. They're is literally no way to know what really happen.
    - Thorrez 5y ago
      Interesting idea. If you were running your own pool then people would likely be tracking your pool and know where you're located. But if you are keeping a low profile and participating in a variety of other pools, then you might go unnoticed. But still, the pool operators might track which IPs are submitting work, and geolocate them, and see which countries are dropping in their work submissions. If you had ran all your stuff through a Chinese VPN historically, then it would make sense. Although usually you want the lowest latency possible when mining to avoid losses due to submitting stale work. A VPN would probably hurt your profits a little.
      - roofwellhams 5y ago
        Do you really think that 1s delay will influence any income... I really doubt it. But considering that there is so much money at stake, an elaborate plan like this... It's possible. Actually it's not even that elaborate. You just need a vpn, and do the split based on news.
        Thorrez 5y ago
        Yes latency does matter. It matters more the faster the block speed is, so for bitcoin it doesn't matter as much as for cryptocurrencies with a faster block speed. But here are some people talking about it: https://www.reddit.com/r/MoneroMining/comments/9sph9w/does_network_latency_to_pool_really_matter/e8rpd40/ https://www.reddit.com/r/MoneroMining/comments/9sph9w/does_n... https://ethereum.stackexchange.com/questions/18201/does-network-latency-significantly-affect-mining-rewards https://ethereum.stackexchange.com/questions/18201/does-netw...
dehrmann 6y ago
You're thinking too small on the impact--China doesn't need to double spend bitcoins. What they could do is cause a loss of confidence in Bitcoin overnight and collapse the price.
- jabbany 6y ago
  How is that even remotely strategically good for China......? These miners are probably making USD or some other foreign fiat at the end of the day which adds to the supply of foreign reserves without needing to use trade... And if they're siphoning power to get around currency exchange limits moving wealth abroad then a traditional crackdown to confiscate their equipment would be much more effective (you can't exactly "hide" a mining operation). Frankly China, with so much mining output, benefits more from seeing crypto moon than crash... (Also "collapsing the price" is something that can be done (and may have actually even already been done in the past) with far far less effort than an attack... (As one example, articles pointing out that "China can do 51% attacks" are much more effective in crashing crypto prices... maybe keep an eye out for those
  - saltyfamiliar 6y ago
    China stands to gain the most from bitcoin mooning at the expense of other countries' currencies. Every yuan exchanged for bitcoin siphons value out of the chinese monetary network and into the global cryptocurrency network. Ideally, if china secured a large portion of bitcoin and then ceased all bitcoin trading within their borders, they could allow other countries to foot the bill of economic instability while the net value of their assets increase. Bitcoin is an economic weapons created by the chinese government.
  - powerapple 6y ago
    Bitcoin is neither good nor bad for China. The minors are not making USD for foreign reserves to be honest, they are mostly a way to transfer wealth out of the country (buying equipments and electricity and sell bitcoins abroad or not selling it at all). That's why China has banned its bank to do crypto related transactions and exchanges mostly. However, it is hard to enforce. You can find many exchange use Bank Transfer, AliPay and WeChat pay. Owning Bitcoins are legal in China. Who knows once the digital RMB is out.
RobLach 6y ago
Why would they be "taken back"? If the the majority of the network agrees on the the new fork who is to say that isn't the de facto "real" fork?
- koheripbal 6y ago
  He means that the real world assets you would buy with your double coins could be taken back. ...ie if you cashed them in for USD at an exchange.
deschutes 6y ago
Undermining trust in bitcoin is a plausible goal. An attacker with that goal wouldn't stop at one attack.
- chii 6y ago
  to what end? Undermining trust in bitcoin isn't a goal on its own - unless you're some mastache twiddling movie villain. If you're a nation state, and want to undermine the legitimacy of bitcoin, you can easily just institute laws to ban it. Much cheaper.
  - quickthrower2 6y ago
    A nation state can’t ban it globally. A 51% attack undermines confidence globally.
    - chii 6y ago
      some nation states can - for example, the US can easily ban it globally. They don't because it does no harm to anyone.
      - quickthrower2 6y ago
        What is the legal mechanism for a unilateral world ban on use of a technology? Closest thing to that I can think of is nuclear proliferation but you’d have to get countries to agree and play strong arm tactics. Possible I guess but not “easily”
        HWR_14 6y ago
        I assume the idea is that a technology that, by definition, can only be used publicly faces a far different threat surface than nuclear proliferation. A significantly powerful actor could exert sufficient force. Russia or the US threatening nuclear war over bitcoin would probably lead to a worldwide ban, although obviously the repercussions would be dramatic. More realistically, the US could state that any bank that does business with bitcoin isn't welcome to participate in the US economy. The US economy is big enough that such a threat might work. This is similar to how the embargoes against Iran worked, and why that Chinese executive is being extradited to the US from Canada. In reality, if Bitcoin got the point of destabilization where the US felt the need to ban it, the effects would probably be widespread enough that the EU, Japan, the various Commonwealth countries would be convinced to take coordinated action.
lottin 6y ago
> can be relatively easily "taken back" This assumes the existence of a legal system with coercive power, which bitcoin doesn't have. That was the point of bitcoin to begin with, in fact.
- jabbany 6y ago
  Uhh, not for the coins themselves but certainly for the goods that were exchanged with them? I mean if you did this IRL, the party providing the goods would just report them as stolen and the traditional legal system can be used to retrieve them. Have fun arguing in court that a 51% attack somehow means you get to keep the thing. This is no different from paying for the thing and stealing the money back IRL. The only thing crypto allows you to do is to distance yourself _physically_ (i.e. you don't actually have to break in and steal money), it means f*ck all _legally_. A similar existing situation analogous for 51% attacks is "paying for something with a personal check and later having it bounce". In fact all major breaches of crypto today involve stealing the coins themselves, which as commenters below have mentioned, cannot be done with a 51% attack---you still don't have the private keys.

roofwellhams 6y ago

What if this drop in hash is to use on the 2nd chain?

Thorrez 6y ago
Well we have a good explanation of the drop: the power outages. Also with 25% hash power you're going to have a hard time doing a 51% attack.
- roofwellhams 6y ago
  Let's say I'm a bad actor in us. I hear about this event in China and I start to do the 2nd chain. You'll think that China region was doing that 25% but maybe they were only doing 1% and I did the other 24%. They're is literally no way to know what really happen.
  - Thorrez 5y ago
    Interesting idea. If you were running your own pool then people would likely be tracking your pool and know where you're located. But if you are keeping a low profile and participating in a variety of other pools, then you might go unnoticed. But still, the pool operators might track which IPs are submitting work, and geolocate them, and see which countries are dropping in their work submissions. If you had ran all your stuff through a Chinese VPN historically, then it would make sense. Although usually you want the lowest latency possible when mining to avoid losses due to submitting stale work. A VPN would probably hurt your profits a little.
    - roofwellhams 5y ago
      Do you really think that 1s delay will influence any income... I really doubt it. But considering that there is so much money at stake, an elaborate plan like this... It's possible. Actually it's not even that elaborate. You just need a vpn, and do the split based on news.
      - Thorrez 5y ago
        Yes latency does matter. It matters more the faster the block speed is, so for bitcoin it doesn't matter as much as for cryptocurrencies with a faster block speed. But here are some people talking about it: https://www.reddit.com/r/MoneroMining/comments/9sph9w/does_network_latency_to_pool_really_matter/e8rpd40/ https://www.reddit.com/r/MoneroMining/comments/9sph9w/does_n... https://ethereum.stackexchange.com/questions/18201/does-network-latency-significantly-affect-mining-rewards https://ethereum.stackexchange.com/questions/18201/does-netw...

dehrmann 6y ago

You're thinking too small on the impact--China doesn't need to double spend bitcoins. What they could do is cause a loss of confidence in Bitcoin overnight and collapse the price.

jabbany 6y ago
How is that even remotely strategically good for China......? These miners are probably making USD or some other foreign fiat at the end of the day which adds to the supply of foreign reserves without needing to use trade... And if they're siphoning power to get around currency exchange limits moving wealth abroad then a traditional crackdown to confiscate their equipment would be much more effective (you can't exactly "hide" a mining operation). Frankly China, with so much mining output, benefits more from seeing crypto moon than crash... (Also "collapsing the price" is something that can be done (and may have actually even already been done in the past) with far far less effort than an attack... (As one example, articles pointing out that "China can do 51% attacks" are much more effective in crashing crypto prices... maybe keep an eye out for those
- saltyfamiliar 6y ago
  China stands to gain the most from bitcoin mooning at the expense of other countries' currencies. Every yuan exchanged for bitcoin siphons value out of the chinese monetary network and into the global cryptocurrency network. Ideally, if china secured a large portion of bitcoin and then ceased all bitcoin trading within their borders, they could allow other countries to foot the bill of economic instability while the net value of their assets increase. Bitcoin is an economic weapons created by the chinese government.
- powerapple 6y ago
  Bitcoin is neither good nor bad for China. The minors are not making USD for foreign reserves to be honest, they are mostly a way to transfer wealth out of the country (buying equipments and electricity and sell bitcoins abroad or not selling it at all). That's why China has banned its bank to do crypto related transactions and exchanges mostly. However, it is hard to enforce. You can find many exchange use Bank Transfer, AliPay and WeChat pay. Owning Bitcoins are legal in China. Who knows once the digital RMB is out.

RobLach 6y ago

Why would they be "taken back"? If the the majority of the network agrees on the the new fork who is to say that isn't the de facto "real" fork?

koheripbal 6y ago
He means that the real world assets you would buy with your double coins could be taken back. ...ie if you cashed them in for USD at an exchange.

deschutes 6y ago

Undermining trust in bitcoin is a plausible goal. An attacker with that goal wouldn't stop at one attack.

chii 6y ago
to what end? Undermining trust in bitcoin isn't a goal on its own - unless you're some mastache twiddling movie villain. If you're a nation state, and want to undermine the legitimacy of bitcoin, you can easily just institute laws to ban it. Much cheaper.
- quickthrower2 6y ago
  A nation state can’t ban it globally. A 51% attack undermines confidence globally.
  - chii 6y ago
    some nation states can - for example, the US can easily ban it globally. They don't because it does no harm to anyone.
    - quickthrower2 6y ago
      What is the legal mechanism for a unilateral world ban on use of a technology? Closest thing to that I can think of is nuclear proliferation but you’d have to get countries to agree and play strong arm tactics. Possible I guess but not “easily”
      - HWR_14 6y ago
        I assume the idea is that a technology that, by definition, can only be used publicly faces a far different threat surface than nuclear proliferation. A significantly powerful actor could exert sufficient force. Russia or the US threatening nuclear war over bitcoin would probably lead to a worldwide ban, although obviously the repercussions would be dramatic. More realistically, the US could state that any bank that does business with bitcoin isn't welcome to participate in the US economy. The US economy is big enough that such a threat might work. This is similar to how the embargoes against Iran worked, and why that Chinese executive is being extradited to the US from Canada. In reality, if Bitcoin got the point of destabilization where the US felt the need to ban it, the effects would probably be widespread enough that the EU, Japan, the various Commonwealth countries would be convinced to take coordinated action.

lottin 6y ago

> can be relatively easily "taken back" This assumes the existence of a legal system with coercive power, which bitcoin doesn't have. That was the point of bitcoin to begin with, in fact.

jabbany 6y ago
Uhh, not for the coins themselves but certainly for the goods that were exchanged with them? I mean if you did this IRL, the party providing the goods would just report them as stolen and the traditional legal system can be used to retrieve them. Have fun arguing in court that a 51% attack somehow means you get to keep the thing. This is no different from paying for the thing and stealing the money back IRL. The only thing crypto allows you to do is to distance yourself _physically_ (i.e. you don't actually have to break in and steal money), it means f*ck all _legally_. A similar existing situation analogous for 51% attacks is "paying for something with a personal check and later having it bounce". In fact all major breaches of crypto today involve stealing the coins themselves, which as commenters below have mentioned, cannot be done with a 51% attack---you still don't have the private keys.