Re:Bitcoin Mining Now Consuming More Electricity Than Many C...
by erikpukinskis on Wednesday November 22, 2017 @05:04PM
(#15761104)
> If there was a successful 51% attack against bitcoin, the hashrate would drop precipitously
Is this really true? There are a ton of factors that mitigate the value/importance of a 51% attack:
1. You still can't spend other people's money. You spend your money twice. Your damage is limited to people who you've transacted with.
2. You can't arbitrarily rewrite history, you can really only play with very recent history. You have to pick a point that you're going back to, and the further back you go the harder it will be to catch up to the original chain. The smaller your margin over 50% the slower the catch-up will be.
3. You're out in the open. Let's say you have 51% power, you still will need hours or days to catch up to the original chain. In that time, people will be able to very clearly see what you are doing and can decide to blacklist your chain. White hats can also bring more computing resources online to make it even harder for you to catch up.
4. During your catch-up period, you need to be able to get your assets out of the blockchain. That's a very specific constraint. If you are trying to buy two boats with the same money, you need to get the first boat off the lot during the time between your first transaction and the moment your fork catches up to the original chain. If the seller of the first boat is watching the blockchain closely, they might even be alerted right when you fork the chain, before you've even caught up. You also need to prevent the seller of the second boat from figuring out what you're up to before you get the second boat off the lot.
5. You're still subject to all existing law enforcement. You still stole a boat.
So who's really at risk? Basically, people doing huge transactions purely within the crypto realm, where the assets can be cleared instantaneously. That's a fairly narrow segment of the market, and those people can use escrow services and other techniques to mitigate their double-spend risk.
Frankly, I think a 51% attack would increase Bitcoin's value, because everyone would see how little value it really gives the attacker. And we'd see all the mitigation strategies we have, which are many. It'd be like the DAO and Parity attacks on ETC, which only seem to have increased confidence, by showing how firewalled those thefts are, and educating people on the choices available to the network for mitigation.
Is this really true? There are a ton of factors that mitigate the value/importance of a 51% attack:
1. You still can't spend other people's money. You spend your money twice. Your damage is limited to people who you've transacted with.
2. You can't arbitrarily rewrite history, you can really only play with very recent history. You have to pick a point that you're going back to, and the further back you go the harder it will be to catch up to the original chain. The smaller your margin over 50% the slower the catch-up will be.
3. You're out in the open. Let's say you have 51% power, you still will need hours or days to catch up to the original chain. In that time, people will be able to very clearly see what you are doing and can decide to blacklist your chain. White hats can also bring more computing resources online to make it even harder for you to catch up.
4. During your catch-up period, you need to be able to get your assets out of the blockchain. That's a very specific constraint. If you are trying to buy two boats with the same money, you need to get the first boat off the lot during the time between your first transaction and the moment your fork catches up to the original chain. If the seller of the first boat is watching the blockchain closely, they might even be alerted right when you fork the chain, before you've even caught up. You also need to prevent the seller of the second boat from figuring out what you're up to before you get the second boat off the lot.
5. You're still subject to all existing law enforcement. You still stole a boat.
So who's really at risk? Basically, people doing huge transactions purely within the crypto realm, where the assets can be cleared instantaneously. That's a fairly narrow segment of the market, and those people can use escrow services and other techniques to mitigate their double-spend risk.
Frankly, I think a 51% attack would increase Bitcoin's value, because everyone would see how little value it really gives the attacker. And we'd see all the mitigation strategies we have, which are many. It'd be like the DAO and Parity attacks on ETC, which only seem to have increased confidence, by showing how firewalled those thefts are, and educating people on the choices available to the network for mitigation.