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by DennisP 1404 days ago
In practice, it's the same as with Bitcoin: you have to get the correct, current software. It's just that the software will include a block hash from a few months back.

You might argue that Bitcoin is defined as the chain with the most hashpower, period. That would remove all subjectivity from Bitcoin, but it would mean that a 51% attacker could arbitrarily change the rules and steal people's funds. That's not how it actually works; a 51% attacker still has to follow the rules of the protocol for their blocks to be accepted by the non-mining nodes, and that means there's social consensus on the correct software to run the protocol.
2 comments
Geee 1404 days ago
That's not how it works. Hashpower decides the canonical chain, not the rules of the system. Hashpower makes sure that the blockchain can't be rewritten. Hashpower can't change the rules of the system, because those blocks would be invalid and rejected by the network.

There's no consensus needed on which rules to use. Everyone can use whichever rules they want, by using different versions of the software. Different rules define a different currency, like euro or dollar. Using the best currency with the best rules is just a game theoretic focal point. Everyone chooses to use the best version of the software, because they assume that everyone else does so too, even in the absence of communication. There is no "correct, current" software in Bitcoin, because it would be a single point of failure.

There's no objective protection against long-range attacks in PoS, because there's no hashpower to prove the canonical chain. It requires the provider of the "correct, current" software to decide which chain is the right one.

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ETH_start 1404 days ago
>>Hashpower decides the canonical chain, not the rules of the system.

No, hash power and the rules decide it. If you have invalid signatures in your blocks, it doesn't matter how much hashpower your fork has, it won't be accepted as canonical by other forks.

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ETH_start 1404 days ago
*by other nodes
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polyomino 1404 days ago
51% attacks can not arbitrarily change the rules nor can they steal funds. They can double spend or prevent finality. Nodes enforce the rules of the network by rejecting blocks they deem invalid.
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