Topic: Is there a possible solution to prevent 51% attack? (Read 592 times)
an alternative can be multi pow algorithm
I remember back in the day, {when Gavin was still lead developer for Bitcoin} ...we had some close calls with 51% attacks
and it was resolved by people shifting to other pools. Most miners know that a 51% attack {if it succeeded} would destroy
investor confidence, so they "Police" themselves. If this was done, people will stop investing in Bitcoin and the price will drop.
No miner wants this to happen, so they willingly shift to other pools.
and it was resolved by people shifting to other pools. Most miners know that a 51% attack {if it succeeded} would destroy
investor confidence, so they "Police" themselves. If this was done, people will stop investing in Bitcoin and the price will drop.
No miner wants this to happen, so they willingly shift to other pools.
Realistically, an attacker would only be able to modify transactions within the past few blocks.
It is more than enough to break down the whole system forever. 
A 51% attack doesn't give you full power over the bitcoin network. The farther back in the blockchain transactions are, the more secured they are against this kind of attack. Realistically, an attacker would only be able to modify transactions within the past few blocks. They would also not be able to make new coins out of thin air - except those received as block mining rewards as usual.
I don't think there will be any solution to prevent this from happening if the owner of the 51% hash power tries to do this attack. This is because the majority of the mining power will then be able to control which blocks to accept. In a simple way, they will be able to reject the blocks which they don't want to mine. So the possibility that their blockchain will be then considered the true blockchain is quite high. They will also be able to double spend any transaction they want once they gain the majority support from the miners. But it is almost impossible to happen knowing that the mining power is spread through out the world. If the miners themselves create a group like the segwit2x did then it might be possible though.
some people leave their other pools and join this big two, can you prevent this? No.. But why doesn't this situation happens?
it does. 
No, the UTXO blocks, the ones that matter for the network, don't have signature data. The witness blocks are not a part of UTXO and therefore are optional. If they are ommited there is no consequence. And it would be more profitable to ommit them.
If you're running an honest and upgraded segwit node, your node will recognise the witness and verify everything in it. Given that most of the network nodes run an upgraded node that is aware, the nodes will automatically reject those blocks with mismatching signatures. You can omit it if you're a miner, you will just be on a fork which the majority of the network isn't following. If no one is following it, your chain is worthless.
Well i mean a few pools together control over 50% so all you have to do is take control of the pools. Considering majority is located in China, it seems like it's something the government could do?
If you do that, how do you prevent all the pool participants from leaving and joining a different pool?
Of course prevention won't be possible because some people may be against it. But also there is a chanse that some people leave their other pools and join this big two, can you prevent this? No.. But why doesn't this situation happens? Why don't they unite? Because everyone wants to be a leader and in some step, there will be big war against each other. So more likely it won't be possible for one man or organization to own 51% of hashrate, it will cause massive protests and etc.
If they are ommited there is no consequence.
You can ommit signatures in your local blockchain from the genesis block.You can delete your local blockchain at all.
But this will not break the current network consensus rules.
No, the UTXO blocks, the ones that matter for the network, don't have signature data. The witness blocks are not a part of UTXO and therefore are optional. If they are ommited there is no consequence. And it would be more profitable to ommit them.
If you are the majority of the hashrate and fork the code then whatever your fork is, is the new coin. This has happened. It happened to moneta verde and probably many other coins. Especially if it is done by a large pool conglomerate.
You can easily fork to form a new coin, absolutely zero hash power is needed. Even if you have a large (100%) of the hashrate and you suddenly fork the chain to have a block reward of 100BTC, every node would reject you and you've created a new coin which no one is following. Individual nodes have the rights to choose what rules they want to follow.And especially with segwit you can steal coins. If you change who sent your coins to be someone else and not you, you in effect stole the coins.
You can't. Having segwit doesn't mean that you can take the coins from anyone without a valid transaction. Blocks still do have signatures in them and nodes require them to validate transactions, segwit or not. No valid signature = Invalid, assuming Segwit nodes. You can't change this fact no matter how much hashpower you have. Anyone selfish would do it. You can do whatever you want. Altcoins get 51%'d all the time. What the most common thing that happens is they fork the code and not give anyone the new code so they are the only ones who can mine it. Then you win every block guarantee.
Also you can double spend whenever you want. You could keep it low key so people don't notice. You can steal coins from zombie wallets and no one would find out.
If you fork the coin and is the only one mining it, no one else would be following them. The network rules would differ and the nodes would reject all of the blocks mined by them. Even if they don't give the code, you can modify it such that is conform to the rules and mine. You are essentially the only one seeing the coin and no one else recognises it as valid. That's completely different from what we're talking about here.Also you can double spend whenever you want. You could keep it low key so people don't notice. You can steal coins from zombie wallets and no one would find out.
You can't steal coins even if you control 100% of the hashrate.
If you are the majority of the hashrate and fork the code then whatever your fork is, is the new coin. This has happened. It happened to moneta verde and probably many other coins. Especially if it is done by a large pool conglomerate.
And especially with segwit you can steal coins. If you change who sent your coins to be someone else and not you, you in effect stole the coins.
Anyone selfish would do it. You can do whatever you want. Altcoins get 51%'d all the time. What the most common thing that happens is they fork the code and not give anyone the new code so they are the only ones who can mine it. Then you win every block guarantee.
Also you can double spend whenever you want. You could keep it low key so people don't notice. You can steal coins from zombie wallets and no one would find out.
If you fork the coin and is the only one mining it, no one else would be following them. The network rules would differ and the nodes would reject all of the blocks mined by them. Even if they don't give the code, you can modify it such that is conform to the rules and mine. You are essentially the only one seeing the coin and no one else recognises it as valid. That's completely different from what we're talking about here.Also you can double spend whenever you want. You could keep it low key so people don't notice. You can steal coins from zombie wallets and no one would find out.
You can't steal coins even if you control 100% of the hashrate.
^^ someone in denial? 51% attack is how every crypto will die the only question is how long can we stall the inevitable. Its like saying that when we created a constitution in america that corporations would never gain control of our government. We lasted 200 years and now the corporations have control. Pretty good run. If bitcoin makes it another 10 years before someone 51% attacks it I will be impressed. Bitcoin has little protection against 51% verses the other altcoins.
So what is the point of destroying Bitcoin with a 51% attack?I don't see why anyone would attempt it if they can't gain anything significant from it. For starters, miners have ASICs and they need Bitcoin to last for as long as possible. Pools collect fees and it wouldn't make sense for them to give up on it. The sheer cost of executing such an attack is the main factor in the execution. The benefit of such an attack wouldn't justify it.
Anyone selfish would do it. You can do whatever you want. Altcoins get 51%'d all the time. What the most common thing that happens is they fork the code and not give anyone the new code so they are the only ones who can mine it. Then you win every block guaranteed. Also you can double spend whenever you want. You could keep it low key so people don't notice. You can steal coins from zombie wallets and no one would find out.
^^ someone in denial? 51% attack is how every crypto will die the only question is how long can we stall the inevitable. Its like saying that when we created a constitution in america that corporations would never gain control of our government. We lasted 200 years and now the corporations have control. Pretty good run. If bitcoin makes it another 10 years before someone 51% attacks it I will be impressed. Bitcoin has little protection against 51% verses the other altcoins.
So what is the point of destroying Bitcoin with a 51% attack?I don't see why anyone would attempt it if they can't gain anything significant from it. For starters, miners have ASICs and they need Bitcoin to last for as long as possible. Pools collect fees and it wouldn't make sense for them to give up on it. The sheer cost of executing such an attack is the main factor in the execution. The benefit of such an attack wouldn't justify it.
Well i mean a few pools together control over 50% so all you have to do is take control of the pools. Considering majority is located in China, it seems like it's something the government could do?
If you do that, how do you prevent all the pool participants from leaving and joining a different pool?
the government could issue a prohibition on bitcoin mining. that wouldn't deter 100% of chinese miners, nor do we know exactly how much hash power controlled by chinese pools actually comes from chinese miners. but i think the effect would be significant. network disruption would be the top concern, but a drastic drop in hash rate would significantly lower the reliability of confirmations. a 51% attack in this context is certainly possible.
i recall there was a lot of talk of selling hardware amidst the recent ban rumors in september. and bitmain certainly has a target on their back in that case. i imagine that major industrial miners would move their operations to new jurisdictions, but i wonder what would happen to the hash rate in the meantime.
I dont think this is a major issue. To even obtain that amount of computing power, just not possible.
There's no need to look for solutions for preventing the 51% attack, because there's no way it is ever going to happen. If we're getting attacked it's by a different way, not this one.
^^ someone in denial? 51% attack is how every crypto will die the only question is how long can we stall the inevitable. Its like saying that when we created a constitution in america that corporations would never gain control of our government. We lasted 200 years and now the corporations have control. Pretty good run. If bitcoin makes it another 10 years before someone 51% attacks it I will be impressed. Bitcoin has little protection against 51% verses the other altcoins.
There is no way to stop it. You can take steps to mitigate the risk. For starters you can block pools like SpreadCoin does. Not sure how effective it is though. Also you can increase blocktime and reduce block size to take away unfair "last winner" advantage. You can make it so only CPU's can mine and not GPU's and ASIC's.
Thats all I can think of for now but pretty much every improvement I am developing is to work on this issue.
Thats all I can think of for now but pretty much every improvement I am developing is to work on this issue.
If you do that, how do you prevent all the pool participants from leaving and joining a different pool?
Do you see any reason to pool participants to join minority pools after successful 51% attack? Jump to: