Who gets to run a slasher node and who gets to agree that its valid to slash a block?

I don't know the specific rules for Ethereum, but in general PoS systems, anyone can slash. All you have to do is submit two different headers for the same block signed by the same validator. This proves the validator is cheating. The person who submits the proof may get to keep some of the validator's slashed money, which is a good incentive to run slashing nodes as this can amount to thousands of dollars per slash, and a good incentive not to double-validate as this can amount to thousands of dollars per time you are caught.

Perversely, since double-validation happens rarely, since it is expensive, the actual interface for slashing on e.g. BSC is not well-documented or user-friendly.

> This proves the validator is cheating.

To whom? Who gets to decide to slash the funds?

I caught you cheating and can prove it. You don't give a shit and control 51% of the network. How do you get punished?

If you control 51% of the network (actually, with Ethereum PoS that number is 67%, as you need 2/3 of the validators to control consensus) and people know you are malicious, people will abandon the network and you will lose your investment because no one is interested in participating in a network controlled by a crook.

It's no different from what would happen in PoW. Can you please stop with the concern trolling?

> If you control 51% of the network (actually, with Ethereum PoS that number is 67%, as you need 2/3 of the validators to control consensus) and people know you are malicious, people will abandon the network and you will lose your investment because no one is interested in participating in a network controlled by a crook.

If that 67% is also true of the slasher voting protocol, then that means you just need 33% of the network to avoid being slashed. Is that wrong?

> Can you please stop with the concern trolling?

Can you please stop trying to claim a moral high ground for no reason?

> just need 33% of the network to avoid being slashed. Is that wrong?

Yes, it is wrong.

How is it wrong? If you need 67% consensus to approve a transaction, and slashing is a transaction, then you can prevent slashing with 33%. What's incorrect about that reasoning?

You won't be prevent slashing with 1/3, you will be merely delaying the block production each time is is proposed. Every time your 1/3 of the nodes attempt maliciously delays of production of a valid block, you will be slashed, and then you won't have 1/3 of the required funds at stake anymore.

But... you can't be slashed unless a block gets processed that supports your slashing, correct?

There is an inactivity leak that gets triggered if you prevent with over 1/3 of your votes from the network reaching consensus. Inactive validators start to leak ETH from their stake until they become less than 1/3 of the total stake and cannot prevent consensus again.

https://eth2book.info/altair/part2/incentives/inactivity

Does the network recognize a difference between being inactive/offline and actively voting no?

There is no difference as far as I know. The network is supposed to finalize blocks that are almost 13 minutes old. If it's not able to do that because there is not sufficient quorum then it starts the inactivity leak phase and the penalties associated.

By the way, there is a bug bounty program. You can earn up to 1M USD per critical bug either in the protocol or its implementations.

Yes, but what is your point? You will be slashed no matter how hard you try to avoid it, unless you have 2/3 of the validators. The closer you are to 2/3, the faster you will be slashed. The system is self-estabilizing.

Social slashing. The honest parts of the community would organize and fork you away.

If you were following the current events on Ethereum, this question has just arisen in the last weeks when the US sanctioned the privacy oriented Tornado Cash contract.

You're right that for a slash to be publicly verifiable, the cheating evidence has to appear on-chain. So indeed there is the question of whether this evidence can be censored...

If you control 51% of the network, the network is fucked.

If you control 20% of the network, the other 80% is following the rules and colluding against you. (Even another 20% that are double-validating themselves are incentivized to slash you)

The people you are discussing this with clearly have no idea how the system actually works and are far out of their depth as far as considering the ways malicious actors interact with it.

In a general PoS system like you describe, what prevents a bistable situation from emerging? If there is any significant level of cheating, then running a slasher is profitable, which makes cheating very unprofitable, driving it to zero. But in the absence of cheating, what's the motivation to develop, maintain, test, and operate a slasher node? Isn't this prone to long periods of time with negligible cheating where all the slashers die out, followed by one big malicious attack that isn't caught promptly?

Possibly. You could even do this if the slashers were active. Just start up your attack instantaneously in between two blocks. Prior to the attack, nobody is cheating. After the attack, nobody is accepting evidence of cheating.

The whole cryptocurrency thing feels like a bit of a metastable equilibrium, but nobody's figured out anything better. Arguably even government-controlled fiat money is not much better - if >50% of the population doesn't like the rules, they will change them - we may be seeing the beginning of this right now, with a lot of people getting dissatisfied with half their income going to the black hole known as "landlords" who own the rights to take your income without producing any value whatsoever.

It might just lead to everyone abandoning your cryptocurrency and using a different one. Since you had to have >50% of the cryptocurrency in order to conduct the attack, you did lose a substantial amount of real-world value (billions or trillions of $) when everyone else stopped using your cryptocurrency.

It's pretty much analogous to if a majority of PoW miners decide to "go their own way" and make a chain where nobody else is invited. What happens then?