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0 sats \ 7 replies \ @optimism 3 Jun \ on: Are you comfortable with Bitcoin's security model? AskSN
What value do you use for "what they're protecting"?
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Yes! With enough share of the total hashrate you can rewrite the whole blockchain. Until before your wallet got its funds. Or until the Genesis block if you will (given enough time).
Apart from being able to block any transactions you try to make (way easier and equally harmful for that wallet).
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Sure you can. But now I nominate a what iirc either Gavin or Sipa called a
preciousblock: a user-enforced checkpoint. I'd do this because the rewritten chain has no value to me. It arguably has no value to anyone I transact with either.So someone will waste tons of sats in electricity for an attack I can revert with a single command.
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That's sounds reasonable. I wonder why isn't there some kind of default in Bitcoin core for automatically setting that. Maybe because of the possibility of a long term disconnection between different parts of the world?
But let's leave that aside. Wouldn't you still think that miners protect all Bitcoin available anyway, because it becomes useless if you can't ever transact with it?
Even if you mined the block with your transaction yourself, evil miners could continue mining from the previous block and do it fast enough so that's the longest chain (even if it's just one block longer). For which the precious block wouldn't save you.
Its hard to determine the value that miners are protecting, the percentage of it that is a good enough security budget, and how this will evolve over time.
What's scary is that as of now, we have a rapidly decreasing security budget relative to the value of the network.
Maybe the tendency changes. Maybe we never stay below the real security threshold. I don't know.
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I wonder why isn't there some kind of default in Bitcoin core for automatically setting that
It's operator decision (docs here) and why "running a node" that you fire & forget doesn't help the chain (though it may help the network if there are many nodes synching - like seeding a torrent.)
Doing anything automatically in this case means that the chain with the most work wins, so the attack you're afraid of would always win within the window then. You need humans in the end: bitcoin isn't automagic internet money because consensus is between humans, not software.
Wouldn't you still think that miners protect all Bitcoin available anyway, because it becomes useless if you can't ever transact with it?
Some miners would. But to overtake in the way you described you need a whole lot more than everyone else. If that happens we'll have big trouble, but no one will revert my transactions because my node will reject these double spends.
However, this is why we're saying that running an economic node is meaningful. Miners have to mine what economic nodes are willing to accept as valid, otherwise their block will be rejected, and that means losing income (especially when income is under pressure, then it becomes even more important that your block doesn't get orphaned, because margins will be tighter.)
After all, like me, you will not take kindly to someone reversing your property either.