You could actually break bitcoin with enough computing power. Bitcoin works on the fact that most of the miners are honest. Someone with enough processing power could rewrite the Blockchain as they want.
Not really, and miners have fantastic financial incentive to remain honest. It’s not altruism. In terms of the attack you are talking about (51% attack) Nobody can amass that much computing power and certainly not quietly, good luck acquiring enough ASICs to do it, let alone enough energy. You’d need your own fab for them which means designing your own ASICs (specialized devices for mining which are orders of magnitude more efficient than regular computers) or stealing designs for them. You’re already into the billions of dollars right there with having your own fab. You can’t buy even half of the processing power you’d need on the open market. A 51% attack is absolutely insanely expensive to do and logistically impossible at this point. And even if they could, the absolute best they can do is temporarily delay transactions or do a double-spend (spend the same BTC twice). They can’t spend money they don’t have the key for and they can’t print extra Bitcoin as all other nodes would reject those transactions as invalid. Doing a double-spend makes no sense because the only benefit of doing so is getting something else in exchange for that BTC. If I’m going to trade say… 1 billion dollars of oil for your BTC, I’m gonna wait for a few blocks of confirmation, even assuming I could transfer that much value that quickly. And whatever you trade has to be more valuable than the cost of a 51% attack which is probably north of a trillion dollars at this point depending on how you do the math. Plus, you know, the legal/extralegal/diplomatic/etc consequences of your actions depending on what you did the attack for.
The attack isn’t a one time thing, your delay only works if you keep attacking. The second you stop, the chain reverse to the “true main chain”. A 51% attack has never happened successfully against Bitcoin and never will at this point. Even at the nation-state scale, Bitcoin is tied in enough to international markets at this point that attacking it could easily cause an international bank run/financial collapse and massive diplomatic problems. And all you’d prove is that you wasted an inconceivably large amount of money to attack a system that picked back up right where it started a few minuted, hours, or days later. Because unless you intend to continue your attack and energy use forever, that’s exactly what would happen. Meanwhile, you’ve pissed off every voter, hedge fund, state retirement fund, business, bank, national treasury, international organization, charity, and legislator who has any sort of exposure to Bitcoin.
You could actually break bitcoin with enough computing power. Bitcoin works on the fact that most of the miners are honest. Someone with enough processing power could rewrite the Blockchain as they want.
Not really, and miners have fantastic financial incentive to remain honest. It’s not altruism. In terms of the attack you are talking about (51% attack) Nobody can amass that much computing power and certainly not quietly, good luck acquiring enough ASICs to do it, let alone enough energy. You’d need your own fab for them which means designing your own ASICs (specialized devices for mining which are orders of magnitude more efficient than regular computers) or stealing designs for them. You’re already into the billions of dollars right there with having your own fab. You can’t buy even half of the processing power you’d need on the open market. A 51% attack is absolutely insanely expensive to do and logistically impossible at this point. And even if they could, the absolute best they can do is temporarily delay transactions or do a double-spend (spend the same BTC twice). They can’t spend money they don’t have the key for and they can’t print extra Bitcoin as all other nodes would reject those transactions as invalid. Doing a double-spend makes no sense because the only benefit of doing so is getting something else in exchange for that BTC. If I’m going to trade say… 1 billion dollars of oil for your BTC, I’m gonna wait for a few blocks of confirmation, even assuming I could transfer that much value that quickly. And whatever you trade has to be more valuable than the cost of a 51% attack which is probably north of a trillion dollars at this point depending on how you do the math. Plus, you know, the legal/extralegal/diplomatic/etc consequences of your actions depending on what you did the attack for.
The attack isn’t a one time thing, your delay only works if you keep attacking. The second you stop, the chain reverse to the “true main chain”. A 51% attack has never happened successfully against Bitcoin and never will at this point. Even at the nation-state scale, Bitcoin is tied in enough to international markets at this point that attacking it could easily cause an international bank run/financial collapse and massive diplomatic problems. And all you’d prove is that you wasted an inconceivably large amount of money to attack a system that picked back up right where it started a few minuted, hours, or days later. Because unless you intend to continue your attack and energy use forever, that’s exactly what would happen. Meanwhile, you’ve pissed off every voter, hedge fund, state retirement fund, business, bank, national treasury, international organization, charity, and legislator who has any sort of exposure to Bitcoin.
Some back of the napkin math for anybody interested https://www.reddit.com/r/Bitcoin/comments/18salm9/the_economics_of_a_hypothetical_51_attack_on/