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What are the attack vectors on PoS. With PoW you need 51% of the mining power to take over the system, which is very labor intensive to set up. With PoS could

What are the attack vectors on PoS. With PoW you need 51% of the mining power to take over the system, which is very labor intensive to set up. With PoS could you take over all coins by buying 51% of the existing coins? So if the market cap of ETH is 200BB spend 100BB to double your money?

eventreduce1 5y ago
Yes and no. If you spend 100BB to buy 51% and then take over the network, eth will have zero value and you loosed 100BB.
- lasagnaphil 5y ago
  Worse, if the overall Ethereum community reaches a consensus that a malicious entity attempted to take over the network, then the devs will fork the blockchain to rollback the particular transactions with the malicious entity, and the new blockchain will keep chugging along as normal while the attacker has just lost a shitton of dollars to buy 100BB. (This is similar to what happened with the DAO previously, although the reason for it was bugs rather than a 51% attack)
  - hanniabu 5y ago
    This is not what happened with the DAO. This is well documented and I suggest you read up on. TLDR, the hacker tried to withdraw the funds and there was a 30 day lockup period so the contract was updated to stop this.
    - lasagnaphil 5y ago
      My understanding was that an illicit fund withdrawing was possible because of a bug in the contract code (more specifically a recursive call loophole), and the community executed a hard fork to return those funds to their original owners. I’m curious as to what I’m misunderstanding here.
- X6S1x6Okd1st 5y ago
  There have been multiple examples of 51% attacks happening and the cryptocurrency it happened to not going to zero. Etherum classic and Bitcoin gold come to mind. They are both in the top 100 still, and both have been 51% attack multiple times.
throw1234651234 5y ago
You don't double your money - at that point the network is compromised and nobody wants your coins. It's a guaranteed way to destroy Ethereum's value, but the only incentive to do it is to troll. Not too many entities globally looking to spend that much for a laugh, even if they could get the necessary funds in liquid form AND manage not to drive up price with their buy orders.
- michael_vo 5y ago
  Perhaps state actors who can print free money would be interested in performing these attacks. Say if a coin was owned predominantly by citizens of one country or if the countries' infrastructure was running on ETH technologies. Like suppose the banking system was running on ETH. Or if Colonial Pipelines used ETH.
  - dodobirdlord 5y ago
    The etherium developers and community have made relatively clear that if someone were to attempt such a thing, the non-malicious members of the community would just fork at the direction of the developers to a chain that is identical except that all of the etherium staked by the attacker is redistributed among the non-malicious verifying nodes, as it would be once the consensus process concluded that an attack was being carried out in a <51% attack scenario.
  - throw1234651234 5y ago
    I can elaborate on any point if interested, but this is covered in the parent. 1. They would drive the price up way past market price in an attempt to make such a large purchase. The cost of a large, rapid purchase is far, far from market price. Only a fraction of the market is willing to sell at current price. 2. If a country wanted to run on Ethereum, they could clone it, since they are giving up the benefits of a GLOBAL system when they take it over. Lmk if you have any questions. Pretty interesting topic given the insane ETH valuation atm, in contrast to, say, Algorand. Network and first move effects, I guess.
Athas 5y ago
Presumably, if someone took that kind of control over Ethereum, its value would rapidly become zero.
- vmception 5y ago
  In practice, different people have utility in the network In most double spent networks, people clamor for the coins so they can have the chance at double spending In PoW networks that’s combined with renting/deploying hash power In PoS networks its just taking over validators Big ole party!
deleted 5y ago
[deleted]
KptMarchewa 5y ago
>So if the market cap of ETH is 200BB spend 100BB to double your money? No one would buy those from you, so at best you can burn money to burn other people's money at a premium.
- Ericson2314 5y ago
  The https://en.wikipedia.org/wiki/Goldfinger_(film) https://en.wikipedia.org/wiki/Goldfinger_(film) strategy, way less efficiently.
sp332 5y ago
You have to find some people willing to sell you that much ETH. Market depth around the current price is obviously not that deep and it would at least cost way more if you could even find that much for sale anywhere.
caballeto 5y ago
Once the attack goal is achieved the Ethereum value will go to zero. It does not make sense to do this by buying coins, but potentially hackers could get control of such big amount of coins by hacking exchanges, thus bringing whole system to collapse. Similar scenario as in Mr. Robot.
- X6S1x6Okd1st 5y ago
  ETC has been 51% attacked 4 times and it's still the 17th largest cryptocurrency. https://www.coindesk.com/crypto-51-attacks-etc https://www.coindesk.com/crypto-51-attacks-etc Furthermore it's become pretty clear from the many attacks on value tokens in Etherum & BSC DeFi that the attacker can move faster that the market and drain any liquidity pools/exchanges that have open offers into something that isn't going to collapse. The theory early on was that the coin cratering b/c of an attack would be an extra deterrent, but the price of coins that have been successfully 51% attacked says otherwise. Here's another cryptocurrency in the top 100 that has suffered many 51% attacks. https://cointelegraph.com/news/bitcoin-gold-blockchain-hit-by-51-attack-leading-to-70k-double-spend https://cointelegraph.com/news/bitcoin-gold-blockchain-hit-b...
  - hanniabu 5y ago
    ETC is PoW, it's a different dynamic than PoS which was the topic of discussion
    - andrewla 5y ago
      If I understand the post you are replying to correctly, the point is that being successfully attacked does not necessarily destroy the value of the coin. Sometimes people argue that a nation state could "shut down" bitcoin for some amount of money -- say $10B. With that, they could buy enough mining equipment to publish empty blocks and throttle the ability to send transactions. Part of my skepticism of this idea is that the bitcoin network is already so throttled but it does not seem to affect the value of the coin negatively. What would be hilarious would be if France decided to shut down Bitcoin, and succeeded, but the value of bitcoin then proceeded to increase 100x.
crazypython 5y ago
You can DDoS normal, non-validating nodes, and if they go offline, they can be unsure which chain is the true chain, because they were not around.. This means your laptop can never sleep, unlike in Bitcoin, where full nodes may go offline and catch up later. People who control stake can refuse to include (censor) transactions, as there is no market competition for transaction inclusion like in PoW. In PoW, if 51% of network power is censoring transactions, then censored transactions can attach a higher fee, which competing miners will use to buy more equipment and mine the censored transactions. These are the ones I know about, that I learned in an evening of research.
- exo762 5y ago
  This is false. At least false for Ethereum's hybrid PoS. It uses Verifiable Delay Function as an element of random number generation process. One can look into number of rounds of VDF and treat them just the way they treat proof of work today. It can be compared to determine which chain is the longer one.
  - jude- 5y ago
    How long till we have a VDF ASIC that lets block producers fuck with this?
    - crazypython 5y ago
      Chia Coin is working on a VDF ASIC so that they can correct for it in advance (essentially selling it at a loss so everyone can own the best VDF) but I'm not sure it's the same VDF as Ether.
jerf 5y ago
In addition to the replies, bear in mind that market cap is a bit of a fiction. If you go on a crazy buying spree to take over the network, you'll raise the price of each token in the price due to your own rising demand. It would be a lot more than $100B.
kipchak 5y ago
The market cap will also increase as you buy loads of coins. For example if I went on coinbase pro, there are people willing to sell up to 50,000 ETH at a maximum price of $6,000, or a total cost of $220,000 million. Of course Coinbase isn't the only market, but if it was and I bought that 220,000 million dollars of ETH the market cap would now be around 700B, at least temporarily. My guess would be at some point people would realize a takeover was occurring and panic, but it seems like a 51% buyout would require an ungodly amount of money and time.
- Consultant32452 5y ago
  It seems like a state actor could do it without much trouble. One important factor is a state actor doesn't necessarily have the profit motive. They could just desire to destroy the ecosystem.
- crazypython 5y ago
  You don't need to buy, you can just get a coalition of people who already own 51% and ask them to do the attack.
Geee 5y ago
You don't have to buy them, you can borrow them. This opens up a certain type of attack where you promise to pay interest to get control of the stake. If you're running a stake pool, you can pay interest on top of the stake reward. It's possible to run a staking yield farm, where you pay interest in a different cryptocurrency that you can mint yourself. These kinds of off-network incentives can disrupt the reward system. It's even possible to incentivize a lot of people to collude in a double spend attack if the rewards can be distributed to the participants.
- DennisP 5y ago
  True, but a double-spend attack would destroy the stake of all the participants.
deleted 5y ago
[deleted]
unique_username 5y ago
Most of these PoS protocols use pBFT consensus (instead of nakamoto consensus) which means it would only require 1/3 instead of 1/2
derivagral 5y ago
Tail risk as I understand it is going to be fun. If your staked nodes lose connectivity (or your pool's) the network can penalize them by slashing the ETH and the stake, right? So after everyone centralizes on a few nodes in the main providers, aren't bad actors heavily incentivized to attack common infra to remove $/power/currency/voting from others and thus shrink the chain? I don't think the network can figure out an "oops, AWS or Comcast went out; my nodes at home or in the cloud shouldn't get slashed" vs "lets sabotage an ISP or network for enough time to trigger penalties and repeat it".
- exo762 5y ago
  You are on point. The solution is (and people do it today) don't run backup nodes, or you will risk getting slashed. Your penalty for missing your vote is very mild - basically not earning the reward for the round.
- eyezick 5y ago
  Yup and accordingly PoS devs have explicitly stated this incentivizes stakers to be spread out, and not only on infrastructure but software, as there are multiple client implementations.
rmhsilva 5y ago
Zack (of https://amoveo.io https://amoveo.io) has a good write up of some attacks here: https://github.com/zack-bitcoin/amoveo-docs/blob/master//other_blockchains/proof_of_stake.md https://github.com/zack-bitcoin/amoveo-docs/blob/master//oth....
seph-reed 5y ago
The attack vectors on PoS are less logical than those of PoW. With PoW, it's all just physics, energy, and math. With PoS it's rich peoples opinions and validation. An attack on PoS will likely be political... and politics tend to slip into war if there's not enough adults in the room.
andrewla 5y ago
It's even easier than that -- all you have to do is get a stake and then brute force mine for an alternate reality where your stake is the sole decision maker for the DAG. You can't really double-spend that way, but you can get a disproportionate amount of the shard rewards. In order to defend against this, other participants will also have to mine for a "more fair" alternate reality, so you end up getting a standstill where nobody can get economic advantage as long as the total power being devoted to preventing chain-shopping is greater than the amount spent on chain-shopping. In the end the energy expenditure would likely be unchanged from the status quo, it would just be hidden behind a facade of inexpensive proof-of-stake validations that conceal the actual work being done to ensure that this is not abused. This way everyone can feel warm and fuzzy because there's no actual way to measure how much work is being done to keep the validation from being monopolized.

eventreduce1 5y ago

Yes and no. If you spend 100BB to buy 51% and then take over the network, eth will have zero value and you loosed 100BB.

lasagnaphil 5y ago
Worse, if the overall Ethereum community reaches a consensus that a malicious entity attempted to take over the network, then the devs will fork the blockchain to rollback the particular transactions with the malicious entity, and the new blockchain will keep chugging along as normal while the attacker has just lost a shitton of dollars to buy 100BB. (This is similar to what happened with the DAO previously, although the reason for it was bugs rather than a 51% attack)
- hanniabu 5y ago
  This is not what happened with the DAO. This is well documented and I suggest you read up on. TLDR, the hacker tried to withdraw the funds and there was a 30 day lockup period so the contract was updated to stop this.
  - lasagnaphil 5y ago
    My understanding was that an illicit fund withdrawing was possible because of a bug in the contract code (more specifically a recursive call loophole), and the community executed a hard fork to return those funds to their original owners. I’m curious as to what I’m misunderstanding here.
X6S1x6Okd1st 5y ago
There have been multiple examples of 51% attacks happening and the cryptocurrency it happened to not going to zero. Etherum classic and Bitcoin gold come to mind. They are both in the top 100 still, and both have been 51% attack multiple times.

throw1234651234 5y ago

You don't double your money - at that point the network is compromised and nobody wants your coins. It's a guaranteed way to destroy Ethereum's value, but the only incentive to do it is to troll. Not too many entities globally looking to spend that much for a laugh, even if they could get the necessary funds in liquid form AND manage not to drive up price with their buy orders.

michael_vo 5y ago
Perhaps state actors who can print free money would be interested in performing these attacks. Say if a coin was owned predominantly by citizens of one country or if the countries' infrastructure was running on ETH technologies. Like suppose the banking system was running on ETH. Or if Colonial Pipelines used ETH.
- dodobirdlord 5y ago
  The etherium developers and community have made relatively clear that if someone were to attempt such a thing, the non-malicious members of the community would just fork at the direction of the developers to a chain that is identical except that all of the etherium staked by the attacker is redistributed among the non-malicious verifying nodes, as it would be once the consensus process concluded that an attack was being carried out in a <51% attack scenario.
- throw1234651234 5y ago
  I can elaborate on any point if interested, but this is covered in the parent. 1. They would drive the price up way past market price in an attempt to make such a large purchase. The cost of a large, rapid purchase is far, far from market price. Only a fraction of the market is willing to sell at current price. 2. If a country wanted to run on Ethereum, they could clone it, since they are giving up the benefits of a GLOBAL system when they take it over. Lmk if you have any questions. Pretty interesting topic given the insane ETH valuation atm, in contrast to, say, Algorand. Network and first move effects, I guess.

Athas 5y ago

Presumably, if someone took that kind of control over Ethereum, its value would rapidly become zero.

vmception 5y ago
In practice, different people have utility in the network In most double spent networks, people clamor for the coins so they can have the chance at double spending In PoW networks that’s combined with renting/deploying hash power In PoS networks its just taking over validators Big ole party!

deleted 5y ago

[deleted]

KptMarchewa 5y ago

>So if the market cap of ETH is 200BB spend 100BB to double your money? No one would buy those from you, so at best you can burn money to burn other people's money at a premium.

Ericson2314 5y ago
The https://en.wikipedia.org/wiki/Goldfinger_(film) https://en.wikipedia.org/wiki/Goldfinger_(film) strategy, way less efficiently.

sp332 5y ago

You have to find some people willing to sell you that much ETH. Market depth around the current price is obviously not that deep and it would at least cost way more if you could even find that much for sale anywhere.

caballeto 5y ago

Once the attack goal is achieved the Ethereum value will go to zero. It does not make sense to do this by buying coins, but potentially hackers could get control of such big amount of coins by hacking exchanges, thus bringing whole system to collapse. Similar scenario as in Mr. Robot.

X6S1x6Okd1st 5y ago
ETC has been 51% attacked 4 times and it's still the 17th largest cryptocurrency. https://www.coindesk.com/crypto-51-attacks-etc https://www.coindesk.com/crypto-51-attacks-etc Furthermore it's become pretty clear from the many attacks on value tokens in Etherum & BSC DeFi that the attacker can move faster that the market and drain any liquidity pools/exchanges that have open offers into something that isn't going to collapse. The theory early on was that the coin cratering b/c of an attack would be an extra deterrent, but the price of coins that have been successfully 51% attacked says otherwise. Here's another cryptocurrency in the top 100 that has suffered many 51% attacks. https://cointelegraph.com/news/bitcoin-gold-blockchain-hit-by-51-attack-leading-to-70k-double-spend https://cointelegraph.com/news/bitcoin-gold-blockchain-hit-b...
- hanniabu 5y ago
  ETC is PoW, it's a different dynamic than PoS which was the topic of discussion
  - andrewla 5y ago
    If I understand the post you are replying to correctly, the point is that being successfully attacked does not necessarily destroy the value of the coin. Sometimes people argue that a nation state could "shut down" bitcoin for some amount of money -- say $10B. With that, they could buy enough mining equipment to publish empty blocks and throttle the ability to send transactions. Part of my skepticism of this idea is that the bitcoin network is already so throttled but it does not seem to affect the value of the coin negatively. What would be hilarious would be if France decided to shut down Bitcoin, and succeeded, but the value of bitcoin then proceeded to increase 100x.

crazypython 5y ago

You can DDoS normal, non-validating nodes, and if they go offline, they can be unsure which chain is the true chain, because they were not around.. This means your laptop can never sleep, unlike in Bitcoin, where full nodes may go offline and catch up later. People who control stake can refuse to include (censor) transactions, as there is no market competition for transaction inclusion like in PoW. In PoW, if 51% of network power is censoring transactions, then censored transactions can attach a higher fee, which competing miners will use to buy more equipment and mine the censored transactions. These are the ones I know about, that I learned in an evening of research.

exo762 5y ago
This is false. At least false for Ethereum's hybrid PoS. It uses Verifiable Delay Function as an element of random number generation process. One can look into number of rounds of VDF and treat them just the way they treat proof of work today. It can be compared to determine which chain is the longer one.
- jude- 5y ago
  How long till we have a VDF ASIC that lets block producers fuck with this?
  - crazypython 5y ago
    Chia Coin is working on a VDF ASIC so that they can correct for it in advance (essentially selling it at a loss so everyone can own the best VDF) but I'm not sure it's the same VDF as Ether.

jerf 5y ago

In addition to the replies, bear in mind that market cap is a bit of a fiction. If you go on a crazy buying spree to take over the network, you'll raise the price of each token in the price due to your own rising demand. It would be a lot more than $100B.

kipchak 5y ago

The market cap will also increase as you buy loads of coins. For example if I went on coinbase pro, there are people willing to sell up to 50,000 ETH at a maximum price of $6,000, or a total cost of $220,000 million. Of course Coinbase isn't the only market, but if it was and I bought that 220,000 million dollars of ETH the market cap would now be around 700B, at least temporarily. My guess would be at some point people would realize a takeover was occurring and panic, but it seems like a 51% buyout would require an ungodly amount of money and time.

Consultant32452 5y ago
It seems like a state actor could do it without much trouble. One important factor is a state actor doesn't necessarily have the profit motive. They could just desire to destroy the ecosystem.
crazypython 5y ago
You don't need to buy, you can just get a coalition of people who already own 51% and ask them to do the attack.

Geee 5y ago

You don't have to buy them, you can borrow them. This opens up a certain type of attack where you promise to pay interest to get control of the stake. If you're running a stake pool, you can pay interest on top of the stake reward. It's possible to run a staking yield farm, where you pay interest in a different cryptocurrency that you can mint yourself. These kinds of off-network incentives can disrupt the reward system. It's even possible to incentivize a lot of people to collude in a double spend attack if the rewards can be distributed to the participants.

DennisP 5y ago
True, but a double-spend attack would destroy the stake of all the participants.

deleted 5y ago

[deleted]

unique_username 5y ago

Most of these PoS protocols use pBFT consensus (instead of nakamoto consensus) which means it would only require 1/3 instead of 1/2

derivagral 5y ago

Tail risk as I understand it is going to be fun. If your staked nodes lose connectivity (or your pool's) the network can penalize them by slashing the ETH and the stake, right? So after everyone centralizes on a few nodes in the main providers, aren't bad actors heavily incentivized to attack common infra to remove $/power/currency/voting from others and thus shrink the chain? I don't think the network can figure out an "oops, AWS or Comcast went out; my nodes at home or in the cloud shouldn't get slashed" vs "lets sabotage an ISP or network for enough time to trigger penalties and repeat it".

exo762 5y ago
You are on point. The solution is (and people do it today) don't run backup nodes, or you will risk getting slashed. Your penalty for missing your vote is very mild - basically not earning the reward for the round.
eyezick 5y ago
Yup and accordingly PoS devs have explicitly stated this incentivizes stakers to be spread out, and not only on infrastructure but software, as there are multiple client implementations.

rmhsilva 5y ago

Zack (of https://amoveo.io https://amoveo.io) has a good write up of some attacks here: https://github.com/zack-bitcoin/amoveo-docs/blob/master//other_blockchains/proof_of_stake.md https://github.com/zack-bitcoin/amoveo-docs/blob/master//oth....

seph-reed 5y ago

The attack vectors on PoS are less logical than those of PoW. With PoW, it's all just physics, energy, and math. With PoS it's rich peoples opinions and validation. An attack on PoS will likely be political... and politics tend to slip into war if there's not enough adults in the room.

andrewla 5y ago

It's even easier than that -- all you have to do is get a stake and then brute force mine for an alternate reality where your stake is the sole decision maker for the DAG. You can't really double-spend that way, but you can get a disproportionate amount of the shard rewards. In order to defend against this, other participants will also have to mine for a "more fair" alternate reality, so you end up getting a standstill where nobody can get economic advantage as long as the total power being devoted to preventing chain-shopping is greater than the amount spent on chain-shopping. In the end the energy expenditure would likely be unchanged from the status quo, it would just be hidden behind a facade of inexpensive proof-of-stake validations that conceal the actual work being done to ensure that this is not abused. This way everyone can feel warm and fuzzy because there's no actual way to measure how much work is being done to keep the validation from being monopolized.