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No. The required amount is greater than 2/3 (67%) not greater than 1/2 (51%) on PoS for Ethereum. Also, see this tweet from Vitalik: https://twitter.com/Vitali

by tsujp 6y ago

No. The required amount is greater than 2/3 (67%) not greater than 1/2 (51%) on PoS for Ethereum. Also, see this tweet from Vitalik: https://twitter.com/VitalikButerin/status/1301298086027821056?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1301298086027821056%7Ctwgr%5E%7Ctwcon%5Es1_&ref_url=https%3A%2F%2Fcointelegraph.com%2Fnews%2Fvitalik-buterin-reveals-why-a-51-attack-on-eth-2-0-would-not-be-fatal https://twitter.com/VitalikButerin/status/130129808602782105... So even if there was a successful first attack from some organised body that's all the time they get.

xur17 6y ago
Great explanation. One interesting aspect of PoS is that attackers really only have 1 shot, and will get slashed or lose their assets. In PoW, you in theory can keep attacking again and again.
naringas 6y ago
> The required amount is greater than 2/3 (67%) I'm not sure that's correct (the tweet doesn't get into any details so I went to ethereum's website https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/#proof-of-stake-and-security https://ethereum.org/en/developers/docs/consensus-mechanisms...) > The threat of a 51% attack still exists in proof-of-stake but it's even more risky for the attackers. To do so, you'd need to control 51% of the staked ETH. Not only is this a lot of money but it would probably cause ETH's value to drop. There's very little incentive to destroy the value of a currency you have a majority stake in. There are stronger incentives to keep the network secure and healthy. The keypoint seems to be that if your attack fails your stake gets destroyed so besides the positive incentives (a good stable network working for all) this system also relies on punishing failed attacks.
Geee 6y ago
So the endgame is that someone owns 99% of all ETH and everyone just accepts it because it's not a threat? Why have a blockchain at all?
nyhc99 6y ago
Correct me if I'm wrong, but you would only need greater than 2/3 of the amount of Ether currently staked, not 2/3 of the total amount of Ether. The amount of staked Ether probably would be less than 10% of the total issued Ether, maybe much less as staking rewards go down.
- tsujp 6y ago
  Correct it is of the staked Ether not total supply. It's an important detail of course and easily missed, a good way for future people stumbling across here to think about it is that any attack only involves those participating in consensus. For Bitcoin consensus is mining. For the beacon Ethereum chain consensus is staking, therefore only staking Ether is relevant.

by tsujp 6y ago

xur17 6y ago

Great explanation. One interesting aspect of PoS is that attackers really only have 1 shot, and will get slashed or lose their assets. In PoW, you in theory can keep attacking again and again.

naringas 6y ago

> The required amount is greater than 2/3 (67%) I'm not sure that's correct (the tweet doesn't get into any details so I went to ethereum's website https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/#proof-of-stake-and-security https://ethereum.org/en/developers/docs/consensus-mechanisms...) > The threat of a 51% attack still exists in proof-of-stake but it's even more risky for the attackers. To do so, you'd need to control 51% of the staked ETH. Not only is this a lot of money but it would probably cause ETH's value to drop. There's very little incentive to destroy the value of a currency you have a majority stake in. There are stronger incentives to keep the network secure and healthy. The keypoint seems to be that if your attack fails your stake gets destroyed so besides the positive incentives (a good stable network working for all) this system also relies on punishing failed attacks.

Geee 6y ago

So the endgame is that someone owns 99% of all ETH and everyone just accepts it because it's not a threat? Why have a blockchain at all?

nyhc99 6y ago

Correct me if I'm wrong, but you would only need greater than 2/3 of the amount of Ether currently staked, not 2/3 of the total amount of Ether. The amount of staked Ether probably would be less than 10% of the total issued Ether, maybe much less as staking rewards go down.

tsujp 6y ago
Correct it is of the staked Ether not total supply. It's an important detail of course and easily missed, a good way for future people stumbling across here to think about it is that any attack only involves those participating in consensus. For Bitcoin consensus is mining. For the beacon Ethereum chain consensus is staking, therefore only staking Ether is relevant.