51% attack would require a collusion of the large group of the miners, and, if successful, will likely cause a massive price drop. Which is the last thing miners want.
P.S. And btw, it's >50% attack, not 51% attack. You don't need that whole extra percent.
They can already do that with a 51% attack anyway. Maybe I'm being naive, but I agree that I can't see the mining community letting such an attack happen.
It's not true that the theoretical 51% attack is cheap. It either requires buying lots of ASICs or paying existing miners to collude with the attacker.
At best, a 51% attack allows double spending a few transactions while destroying the miner’s business.
The thing is, what you can do with a 51% attack is very limited and the big services are probably going to be aware of it. Best case scenario is that you halt transactions for a few hours. This will cost a few million dollars with, maybe, no possible reward.
The next problem is that this calculation is based on the current hash-rate cost. However, you don't have that much hardware and it'll be close to impossible to rent half of bitcoin mining rate. So such an attack will be order of magnitudes more expensive if even possible.
I hadn't considered this before, but that's a really compelling reason that a 51% attack would not be worth anyone's while. Seems like a successful 51% attack would just wreck bitcoin, and there wouldn't be any way to cash out.
> 51% attack would require a collusion of the large group of the miners
If you can shut off 70% of all the miners (because they run backdoored hardware), then you only need >50% of the remaining 30%, no? Which should be a lot easier.
Whats the point of that ? A miner can confirm non-standard transactions right now when he mines a block but no one would accept it. Point of 51% attack is to surreptitiously double spend and nothing else.
Who is seriously going to try and execute a 51% attack? It would be so incredibly expensive, you would have to keep spending more as people added hash power to shut you out, and most importantly if your attack worked you would instantly undermine the security of the blockchain making all the currency you've stolen worthless!
Do you think the headline is correct in labeling this as a 51% attack? The other argument would be that developers are trying to push through a contentious fork (mostly but not only contested by miners and mining pools), and mining nodes are planning to not adopt the proposed change?
51% attacks are mostly overblown. If a group decides to engage in a 51% attack, all they are doing is effectively revoking their own license to print money - which is what having a > 51% mining capacity in a major crypto translates to. Bitcoin is a public ledger and double spend transactions would be completely visible to all. All this means is that the coin would end up getting forked, similar to what happened when Ethereum screwed up - and it continued on with minimal fanfare. And in that case their screw up was of their own fault instead of something inherent - even fewer people would be inclined to stay on a Bitcoin line that has been 51%'d.
Rolling with the mine analogy, a 51% attack is equivalent our group that sent in a million miners changing the diamond mine into a 'glass' one. It becomes fake, and loses nearly all of its value and people move to the new 'real' mine. You do nothing except critically hurt yourself.
As the mining rewards keep lowering it's getting to the point here someone is going to do this for the lulz. As to cost you can sell all your coins before doing a 51% attack. Short the market and at some point it might even be proffitable to do so.
To be in the position of being able to do a bitcoin 51% attack however you would have had to sunk enormous costs into buying ASIC miners. The minute everyone finds out that a 51% attack occurs you will have pressure to change the mining algorithm and suddenly all your miners are worthless.
Yes. A 51% attack is a popular whipping boy. It's not as dangerous as it seems.
The price would tank, for sure. But your money won't be gone. And eventually when the attack dies down you'll get your wealth back.
However, it remains a very interesting way for governments to completely destroy Bitcoin. It's the only way, and they have to do it now before centralized, dedicated mining facilities come online. It would disrupt the price enough and scare away enough people that the threat BTC poses will vanish, at least for awhile. And that will discourage miners from setting up facilities, such that the governments can just beat them again if they have to.
But it's already almost impossible.
The difference is intent. It's not really much of a problem for a miner to have >51% share. They're there to make money. And Satoshi pointed out they'll probably just keep mining rather than devaluing their own wealth.
But an organized, worldwide governmental campaign against cryptos would be another matter.
Miners only control transaction inclusion/ordering. That's the only thing that a 51% attack will grant you. You still can't forge coins or make unauthorized transfers. You can do double spend attacks and tank the trust of the network, but I'm skeptical whether that's actually worth it. It's probably cheaper to send death squads to users/merchants/exchanges.
No they won't. As the cost of 51% attack is actually the cost of fee of cancelled transaction(and subsequent ones) plus created coins. The attacker can collect all the fees also from those blocks they mined for attack...
Ofc, if the mining is sufficiently large that it is impossible for anyone to collect enough power, then sure. But that is quite expensive proposition in general...
Right. The protections against this are already baked into the protocol.
51% attacks don't make sense because you're hurting yourself 51% and hurting everyone else 49%.
And for this theoretical attack you'd probably need to sustain 90%+ hash power for a long time.
Your first hurdle will be producing enough ASICs to surpass current hashrate by nearly 10x. Solve that problem and you'll need a massive amount of energy and you'll have to set up huge mining facilities in various locations to prevent crippling local power grids.
This would take years to plan & execute. A lot of people would have to be involved. Good luck keeping it a secret. Network hash rate will continue to increase while you're building this infrastructure.
If by some miracle you've pulled this off, Bitcoin users will switch to a fork of Bitcoin that uses a different mining algorithm and your entire investment is now completely worthless.
In practical terms a 51% attack is not good, but actually has a fairly straight-forward solution to solve. Change the PoW. A 51% attack can't steal your coins, only restrict your spending them for the length of time they are conducting the attack. So the issue isn't that you have 51% attack possibility, but that people think you do, and furthermore think you're going to abuse it. If a government attacked it, they'd simply hard-fork away from the mining algorithm, and millions of dollars of hardware investment gets flushed down the toilet.
P.S. And btw, it's >50% attack, not 51% attack. You don't need that whole extra percent.
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