Comment by nootropicat | Hacker News Reader

Comment by nootropicat | Hacker News Reader

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Multiple aspects. PoS offers much, much stronger security than PoW while being about 4000x cheaper to run and sustainably decentralized. Sharding (along with rollups) allows for a truly global scale platform - over 100k TPS, potentially 1M, while still running on normal computers in people's homes. PoS is a requirement for sharding, as dividing security under PoW would make each shard too easy to attack.

Last but not least, full eth2 turns eth into a positive yield asset, a share in ethereum (real income depends on fees paid by users - ethereum already dominates).

https://cryptofees.info/

To not overhype, the current launch is really an incentivized testnet only for PoS itself - real ethereum still runs on PoW as it was. It's important because it shows that after long delays eth2 is finally starting to happen, and because consensus itself is like a car that can drive without transporting anything or anyone - not very useful at the moment, but changes required to make it useful are relatively small compared to building the car from the ground up.

> PoS offers much, much stronger security than PoW

Uh, why do you say that?

The security of PoS in fact ought to be much LOWER than the security of PoW:

The goal of requiring proof of work is that you cannot just send multiple versions of the same transaction into different areas of the network to double-spend your money - because you need to commit work for producing a block, and due to consuming energy you can't fake that.

Well, you can compute two (or more) blocks in parallel, but then you'll spend half of your available CPU (or ASIC nowadays) cycles on each block, thus cutting your speed in half. So the non-malicious competitors on the network will produce more blocks meanwhile because they're not splitting their computation power, and thus your fake blocks will get invalidated because they're on the shorter chain.

With PoS on the other hand you can create as many fake blocks as you want and spam them to the network. The only security is the hope that the random network topology arbitrarily results in the double-spending blocks arriving at the targets under attack after the other blocks arrive.

But if you run thousands of nodes on the cloud and thus have better network connectivity than the victims you can make your double-spend blocks arrive first at the victims.

So:

- PoW: Relies on physical limits, you need to have physical hardware and physical energy to conduct an attack.

- PoS: Relies on the network connectivity of the attacker being hopefully worse than the connectivity of the non-malicious network. Who can guarantee that? Nobody.

Thanks for answering questions I’ve had for a long time about POS. Do you have any links to share on the subject?

Google "nothing at stake problem".

This is completely untrue and has been since 2014. The solution is that validators are "slashed" and lose their tokens if they have been found to sign two blocks at the same height.

What has happened in 2014? Is that a time when brain-washing campaign in crypto-media has been started? "Slashing" is not a solution to this problem.

Vitalik Buterin came up with a solution for the nothing-at-stake problem: https://blog.ethereum.org/2014/01/15/slasher-a-punitive-proo...

Also, I'm not sure why you and the other commenter are so argumentative about this. There are several PoS networks out there such as Cosmos, Tezos, etc, holding more than a billion dollars. If there was an issue, someone would have hacked them by now.

> Vitalik Buterin came up with a solution for the nothing-at-stake problem

Is that a link to an article from a peer reviewed academic journal?

> There are several PoS networks out there such as Cosmos, Tezos, etc, holding more than a billion dollars. If there was an issue, someone would have hacked them by now.

I'll give you a hint: "slashing" is not a thing that sustains security of these networks.

Where did he claim it was a peer reviewed journal?

Don't you think this claim should be supported by some reputable secondary source?

Security deposits of attackers in ethereum are slashed, up to 100%, in case of an attack. The value at stake can potentially grow into hundreds of billions, much more than any PoW chain can hope to accumulate in mining revenues in its entire existence.

Last but not least, there's no way to delete PoW attacker's gpus, but hostile stake is always going to be slashed. Asic pow chain can be forked - once - to a gpu pow, but that's it, and after that there's no recourse to sustained attacks. This property virtually guarantees that no attack against PoS with slashing is ever going to happen.

https://vitalik.ca/general/2020/11/06/pos2020.html

> Security deposits of attackers in ethereum are slashed, up to 100%, in case of an attack.

What defends against the attacker configuring his nodes to just not relay the blocks which slash his deposits, by having a majority in the network connectivity, and thereby convincing victim nodes that he in fact is the victim of false slashing because the victims will only discover the slash-claims much after the attackers "valid" blocks?

Or in other words:

Isn't the slashing mechanism also reliant upon mere hope that the network topology randomly happens to be in favor of non-malicious peers?

You seem to assume that the attacker has control over the entire internet.

Ethereum has 11 000 nodes currently: https://www.ethernodes.org/

There are probably many botnets of IoT devices with 10x that many nodes, aren't there?

So a single botnet could probably ensure that a target victim has the majority of peer connections to the attacker.

If a validator signs two blocks at the same height, they will be slashed, lose their tokens, and not be able to participate in consensus. They get slashed when anyone submits evidence of them doing this. This trivially solves the "nothing at stake" problem from 2014 that you wrote your long original comment about.

If I understand it correctly, you are now saying that someone would DDOS the entire gossip network, completely halting any more production of blocks so that their slashing doesn't go through?

We're not even talking about "nothing at stake", or anything having to do with PoS anymore. We're just talking about a massive DDOS of an entire network. Node operators in PoS networks, as well as Bitcoin, have ways of dealing with DDOS which are the same as how anyone deals with it, and I don't need to get into them here.

If someone was able to overcome these DDOS mitigations and completely prevent a PoS network from receiving any legitimate transactions, they could do this to Bitcoin as well.

> They get slashed when anyone submits evidence of them doing this.

Who will record this "evidence" to the blockchain? Anyway there will be two versions of the blockchain. In one of them attacker's stake was not slashed and there is no any "evidence" of his malicious actions.

The "evidence" is two blocks, with the same block height, both signed by the attacker.

Not sure what these two versions of the blockchain you're talking about are. Signing two blocks at the same height with the same chain id is the slashable offense. It doesn't matter what's in them.

If the attacker wants to have his own blockchain off in the corner where he has all the money, nobody cares.

> Not sure what these two versions of the blockchain you're talking about are.

Really?! One version is "Vitalik's fork" and another one is "non-Vitalik's fork". Which one of them is a valid chain? Any idea?

Assume the attacker is Vitalik and there an "evidence" of his attack. Who will dare to slash him? Vitalik won't include this evidence into "Vitalik's fork". If Vitalik wants to have his own blockchain, nobody cares, isn't it?

Not OP... but one big difference between PoW and PoS is that:

when a PoW block is mined, there's no way to know how much hidden equipment is out there mining a parallel chain, which could suddenly appear and take over with more accumulated work. You hope the malicious actor doesn't have 51%, but there's no way to actually prove that they aren't out there.

with PoS on the other hand, the set of validators who are voting on a block is known many blocks in advance. so say a malicious validator has X% of the voting power on a given block: he can't refuse to relay the other votes, because it will be obvious to all other nodes that he only speaks for X%, and what he's broadcasting lacks quorum, because the other (100-X)% votes are missing.

Whereas the other (100-X)% group will be actively broadcasting that they're slashing his stake; and if (100-X) has quorum, those votes will be accepted as valid by all the nodes on the network, regardless of what the malicious actor decides to broadcast.

TLDR: under PoW, silence is assumed to be absence of dissent, since number of miners out there is unknown. Whereas under PoS, silence still allows proving lack of quorum (since the voters are known well in advance), so censorship doesn't let a malicious validator legitimize their vote.

If the attacker has 2/3 of the entire stake then the only option is to manually coordinate a fork to a chain without his censorship, allowing protocol penalties to run its course. A direct analogue of an asic PoW fork in case of a sustained attack.

>and thereby convincing victim nodes that he in fact is the victim of false slashing because the victims will only discover the slash-claims much after the attackers "valid" blocks?

It's not possible for 'false slashing' to occur, because slashing requires presenting conflicting votes.

>Isn't the slashing mechanism also reliant upon mere hope that the network topology randomly happens to be in favor of non-malicious peers?

topology doesn't matter in this case, 2/3+ consensus is asynchronous. 2/3 of stake is required to finalize blocks, so the attacker would finalize his own chain without slashing.

There are some ideas about 99+% proof consensus which rely on topology and nodes being online (which means they can observe that censorship is happening) but it's not currently implemented. Eventually I expect it to happen, making attacks a practical impossibility, by coupling asynchronous 2/3+ consensus guarantee with synchronous 99+% guarantee, effectively automatically coordinating anti-censorship forks.

https://vitalik.ca/general/2018/08/07/99_fault_tolerant.html

Why did you not add "Who can guarantee that? Nobody." to the PoW description as well?

Exactly. As they say, first step is always the hardest. The switch from PoW to PoS was monumental and I'm glad they took the time to execute so well. This is a great step forward for Ethereum

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