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There is absolutely no way to 51% attack a major coin like Bitcoin for as little as $700k an hour. They are extrapolating from Nicehash's mining rental prices,

by Meekro 7y ago

There is absolutely no way to 51% attack a major coin like Bitcoin for as little as $700k an hour. They are extrapolating from Nicehash's mining rental prices, but Nicehash doesn't have anything like the capacity you'd need. You can see here[1] that nicehash has about 500 PH/s (500,000 TH/s) available for rent. However, Bitcoin's total hash rate right now is 100,000,000 TH/s[2]. This means that if you rented out the entire nicehash market, you'd have 0.5% of the hash rate you need. Could you get the other 99.5% by buying lots of mining hardware? Theoretically yes, but realistically no. Bitmain is a major supplier of this kind of hardware, so let's use their prices as a reference. They're currently promoting a 67 TH/s unit for $1585 [3]. You would need more than 1.4 million of these units, at a cost of over $2.2 billion dollars. Not that any supplier can fill an order like that quickly. And we haven't even gotten to the power and operations costs. You'd need dozens of huge data centers to run all this hardware, each one consuming astronomical amounts of electricity. You'd probably pick your data center locations based on availability of cheap power and labor, and you'd become a major commercial presence in each of those towns. The local papers would have photos of you shaking hands with the mayor as your data centers open up. Everyone would know what you're doing, including the FBI. [1] https://www.nicehash.com/my/marketplace/SHA256 https://www.nicehash.com/my/marketplace/SHA256 [2] https://www.blockchain.com/en/charts/hash-rate https://www.blockchain.com/en/charts/hash-rate [3] https://shop.bitmain.com/product/detail?pid=00020200117151322700cA9h5cat0694 https://shop.bitmain.com/product/detail?pid=0002020011715132...

RL_Quine 7y ago
Why are you assuming that hashrate would be obtained legally? If you're already assuming criminality, go all out! BGP route hijack the unencrypted, unauthenticated mining traffic and call it your own. Cost is basically nothing to do so, other than some jail time.
- SilasX 7y ago
  Can you clarify what you mean by hijacking mining traffic? If you mean the traffic of mining pools communicating their solutions to the pool's "mother brain", those are already cryptographically attached to a solution that pays out to specified addresses. You can't substitute the transactions in the block/solution without redoing the PoW. That's why miners can't steal a pool's solutions to begin with.
  - RL_Quine 7y ago
    All miners connect to pools using a protocol called stratum. This is JSON piped over TCP with newline terminations. There is no authentication for this protocol and no encryption. You can simply intercept the communication here and have all the miners on a pool actually mine for your replacement pool, and nobody will ever catch on until its far too late. > If you mean the traffic of mining pools communicating their solutions to the pool's "mother brain", those are already cryptographically attached to a solution that pays out to specified addresses. That's not correct in practice. There's no authentication of the work going to the miner at all, so an attacker can just change the destination before the miner even sees the work.
    - aphextim 7y ago
      When I was toying around with mining some alt coins with GPUs a few years back I had the thought when joining a mining pool on say supernova, what is to prevent someone from doing an attack and convincing the pool to send my coins to them instead at a level 'under the hood' and beyond my understanding. Or get the entire pool to act in a way that is for their own personal gain. I know there had been guides on how to set up your mining rigs, setup the batch files etc. These were all guides written by other people and I could see how in this newly created space there was room for nefarious actors to try to convince people to mine in a pool, but not give them the rewards they deserved or scammed them in some other way. I also thought about someone hacking entire pools' hash-rates to be used for their own purposes rather than trying to figure out the next block on whatever chain it was running. This would allow someone to 'steal' the hash power of expensive rigs and redirect the power to their own wallets. My understanding of all these protocols is very limited to what is regurgitated from others. When it comes to reading the bitcoin whitepaper I was only able to comprehend up until section 11 on page 6 where it got into the calculations, at which point I got lost as I am not that good at math. Thank you for the insight.
      - hinkley 7y ago
        If you kept all of the coins from a pool, you'd be caught. But would I ever know if you lied about the pool's GH/s rate and kept half of the coins?
- bufferoverflow 7y ago
  That's not how any of this works. There's no massive mining traffic. Most of the mining is done in private data centers. They only broadcast their transactions when they "solve" the hash.
  - RL_Quine 7y ago
    This is exactly how it works! Most miners are connected to pools like slushpool, f2pool, etc over unencrypted an unauthenticated links. If you can modify this traffic you can steal the hashrate, because you can modify the work being sent to the miners before they do any hashing.
  - EthanHeilman 7y ago
    These private mining datacenters typically get their block templates from pool servers. Miners communicate with the pool servers over the internet. Control the pool server control the mining power.
- e12e 7y ago
  Is it clear that an attack on a crypto currency would be illegal? I suppose it might fall under wire fraud... Like some hacking does?
xur17 7y ago
> There is absolutely no way to 51% attack a major coin like Bitcoin for as little as $700k an hour. They are extrapolating from Nicehash's mining rental prices, but Nicehash doesn't have anything like the capacity you'd need. You are correct - the nicehash-able column represents the amount of necessary hash power that is available via nicehash. If it's below 100% the attack cost is also greyed out. Disclaimer: I build crypto51.
- henryfjordan 7y ago
  the grey you picked is pretty hard to distinguish from the black. The italics are nice though. Maybe add a little icon like this "no power" one: https://thenounproject.com/term/no-power/632253/ https://thenounproject.com/term/no-power/632253/
jayd16 7y ago
So I have a fun thought. You can cantrip your ill gotten coin into more compute. Assuming you could work your way up and own every exchange before anyone caught on (not realistic), could you work up enough funds to buy enough general cloud compute to overtake BTC?
sharno 7y ago
How about a malicious country/government that is capable of doing this?
hinkley 7y ago
Nicehash has .99% of what you need to have 51% of the hashrate, not .5%. But that's still too tiny. However. You don't need 51% of the hashes to have the longest chain. The longest chain is a lottery. If you had 25% of the TH/s out there, there are 3x as many hashes you don't control as do. The odds are 1:3 that you will still find the next hash. If that weren't the case, there'd be no point at all in me having .0001% of the TH/s. I'd be better off setting the money on fire to heat my house. Bitcoin doesn't have a consensus algorithm on two counts. The obvious one is that everyone takes the longest chain, regardless of whether everyone already agreed to a shorter chain. In Raft, your history can roll back if there's a partition. In Bitcoin, things can be rolled back even if everyone is online. I need one attack (rewrite history), not two (rewrite history + DOS attack), and because of that, nobody but my pocketbook notices if I try and fail. The second one is that there is no consensus on what transactions to include in the next hash. Any hasher could blacklist transactions that are unfavorable to them without really affecting their odds of finding the next hash. I think it's assumed that it's not in the interest of either mining hardware owners or frequent cryptocurrency spenders to do this, as they would destabilize their own investment. That only borrowed hardware would be used that way, and on short bursts of purchases. But is that really true? Or is there a zero-day attack out there already being used or waiting to be found? I'm thinking of the epic embezzling scandals that have turned up. How many people out there were never caught, or were insufficiently prosecuted? Employees are usually subject to the laws where the office is located. These people could be on the other side of the world.
- AgentME 7y ago
  If you had 1/4 the hash power, it's true that you have 1/4 chance of creating a block before anyone else, but to be clear, doing that once isn't enough to do a double-spend attack of a transaction with some N confirmations (usually people would aim for N=6). There's only a 2% chance an individual attempt would pull that off for 6 confirmations in a row when using 1/4 the global hash power, and the whole time you're attempting this, your hash power isn't making money mining unless you succeed. On average, you would make $144,000 just from the block rewards from mining for that much time with 1/4 global hashpower, so the expected amount of failures are very expensive in opportunity costs. If I'm doing probability right, then at a 2% chance, you could expect to fail about 25 times on average before succeeding, so 25 failures adds up to $3.6 million of expected opportunity cost. (This isn't counting the cost in acquiring 1/4 global hashpower to begin with.) You would have to double-spend a lot of transactions to make that worth it, and people are probably going to wait for more than 6 confirmations on bigger transactions, which means a much larger attack would have to be done to target those.

by Meekro 7y ago

RL_Quine 7y ago

Why are you assuming that hashrate would be obtained legally? If you're already assuming criminality, go all out! BGP route hijack the unencrypted, unauthenticated mining traffic and call it your own. Cost is basically nothing to do so, other than some jail time.

SilasX 7y ago
Can you clarify what you mean by hijacking mining traffic? If you mean the traffic of mining pools communicating their solutions to the pool's "mother brain", those are already cryptographically attached to a solution that pays out to specified addresses. You can't substitute the transactions in the block/solution without redoing the PoW. That's why miners can't steal a pool's solutions to begin with.
- RL_Quine 7y ago
  All miners connect to pools using a protocol called stratum. This is JSON piped over TCP with newline terminations. There is no authentication for this protocol and no encryption. You can simply intercept the communication here and have all the miners on a pool actually mine for your replacement pool, and nobody will ever catch on until its far too late. > If you mean the traffic of mining pools communicating their solutions to the pool's "mother brain", those are already cryptographically attached to a solution that pays out to specified addresses. That's not correct in practice. There's no authentication of the work going to the miner at all, so an attacker can just change the destination before the miner even sees the work.
  - aphextim 7y ago
    When I was toying around with mining some alt coins with GPUs a few years back I had the thought when joining a mining pool on say supernova, what is to prevent someone from doing an attack and convincing the pool to send my coins to them instead at a level 'under the hood' and beyond my understanding. Or get the entire pool to act in a way that is for their own personal gain. I know there had been guides on how to set up your mining rigs, setup the batch files etc. These were all guides written by other people and I could see how in this newly created space there was room for nefarious actors to try to convince people to mine in a pool, but not give them the rewards they deserved or scammed them in some other way. I also thought about someone hacking entire pools' hash-rates to be used for their own purposes rather than trying to figure out the next block on whatever chain it was running. This would allow someone to 'steal' the hash power of expensive rigs and redirect the power to their own wallets. My understanding of all these protocols is very limited to what is regurgitated from others. When it comes to reading the bitcoin whitepaper I was only able to comprehend up until section 11 on page 6 where it got into the calculations, at which point I got lost as I am not that good at math. Thank you for the insight.
    - hinkley 7y ago
      If you kept all of the coins from a pool, you'd be caught. But would I ever know if you lied about the pool's GH/s rate and kept half of the coins?
bufferoverflow 7y ago
That's not how any of this works. There's no massive mining traffic. Most of the mining is done in private data centers. They only broadcast their transactions when they "solve" the hash.
- RL_Quine 7y ago
  This is exactly how it works! Most miners are connected to pools like slushpool, f2pool, etc over unencrypted an unauthenticated links. If you can modify this traffic you can steal the hashrate, because you can modify the work being sent to the miners before they do any hashing.
- EthanHeilman 7y ago
  These private mining datacenters typically get their block templates from pool servers. Miners communicate with the pool servers over the internet. Control the pool server control the mining power.
e12e 7y ago
Is it clear that an attack on a crypto currency would be illegal? I suppose it might fall under wire fraud... Like some hacking does?

xur17 7y ago

> There is absolutely no way to 51% attack a major coin like Bitcoin for as little as $700k an hour. They are extrapolating from Nicehash's mining rental prices, but Nicehash doesn't have anything like the capacity you'd need. You are correct - the nicehash-able column represents the amount of necessary hash power that is available via nicehash. If it's below 100% the attack cost is also greyed out. Disclaimer: I build crypto51.

henryfjordan 7y ago
the grey you picked is pretty hard to distinguish from the black. The italics are nice though. Maybe add a little icon like this "no power" one: https://thenounproject.com/term/no-power/632253/ https://thenounproject.com/term/no-power/632253/

jayd16 7y ago

So I have a fun thought. You can cantrip your ill gotten coin into more compute. Assuming you could work your way up and own every exchange before anyone caught on (not realistic), could you work up enough funds to buy enough general cloud compute to overtake BTC?

sharno 7y ago

How about a malicious country/government that is capable of doing this?

hinkley 7y ago

Nicehash has .99% of what you need to have 51% of the hashrate, not .5%. But that's still too tiny. However. You don't need 51% of the hashes to have the longest chain. The longest chain is a lottery. If you had 25% of the TH/s out there, there are 3x as many hashes you don't control as do. The odds are 1:3 that you will still find the next hash. If that weren't the case, there'd be no point at all in me having .0001% of the TH/s. I'd be better off setting the money on fire to heat my house. Bitcoin doesn't have a consensus algorithm on two counts. The obvious one is that everyone takes the longest chain, regardless of whether everyone already agreed to a shorter chain. In Raft, your history can roll back if there's a partition. In Bitcoin, things can be rolled back even if everyone is online. I need one attack (rewrite history), not two (rewrite history + DOS attack), and because of that, nobody but my pocketbook notices if I try and fail. The second one is that there is no consensus on what transactions to include in the next hash. Any hasher could blacklist transactions that are unfavorable to them without really affecting their odds of finding the next hash. I think it's assumed that it's not in the interest of either mining hardware owners or frequent cryptocurrency spenders to do this, as they would destabilize their own investment. That only borrowed hardware would be used that way, and on short bursts of purchases. But is that really true? Or is there a zero-day attack out there already being used or waiting to be found? I'm thinking of the epic embezzling scandals that have turned up. How many people out there were never caught, or were insufficiently prosecuted? Employees are usually subject to the laws where the office is located. These people could be on the other side of the world.

AgentME 7y ago
If you had 1/4 the hash power, it's true that you have 1/4 chance of creating a block before anyone else, but to be clear, doing that once isn't enough to do a double-spend attack of a transaction with some N confirmations (usually people would aim for N=6). There's only a 2% chance an individual attempt would pull that off for 6 confirmations in a row when using 1/4 the global hash power, and the whole time you're attempting this, your hash power isn't making money mining unless you succeed. On average, you would make $144,000 just from the block rewards from mining for that much time with 1/4 global hashpower, so the expected amount of failures are very expensive in opportunity costs. If I'm doing probability right, then at a 2% chance, you could expect to fail about 25 times on average before succeeding, so 25 failures adds up to $3.6 million of expected opportunity cost. (This isn't counting the cost in acquiring 1/4 global hashpower to begin with.) You would have to double-spend a lot of transactions to make that worth it, and people are probably going to wait for more than 6 confirmations on bigger transactions, which means a much larger attack would have to be done to target those.