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Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

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Re: Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

#101

Post by dpiers »

baddox wrote: post #58
49bc wrote: post #8

Satoshi really downplayed 51% attacks in his/her original whitepaper[1]: > The incentive may help encourage nodes to stay honest. If a greedy attacker is able to assemble more CPU power than all the honest nodes, he would have to choose between using it to defraud people by stealing back his payments, or using it to generate new coins. He ought to find it more profitable to play by the rules, such rules that favour h…

But wouldn't the long-term honest mining be more profitable than a single hit and run? Kinda the same reason that when you go to a restaurant the restaurant owners almost always exchange food for money rather than rob you and leave town forever. If you own a restaurant it's generally more profitable to run it honestly than run away with a one-time dishonest payoff.

Not if it destroys the credibility of a rival coin, which I suspect could be the case here. Many in the "real Bitcoin" community call Bitcoin Cash a fraud because its existence reveals the specious value of their "real" cryptocurrency.

Executing a double spend attack on Bitcoin Cash would be a massive success for Bitcoin owners. Same goes for Bitcoin Gold.

You could even create a mining pool/network - let's call it CoinFucker - where every now and then the pool's resources were diverted to attack a rival coin. Doing so damages that coin's reputation, and in doing so reduces the competition. This would be a great way for the majority of mining/computational power to squash would-be rivals.

Re: Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

#102

Post by Zalastax »

mike-cardwell wrote: post #84
celticninja wrote: post #63

Earlier quoted context omitted.

it exists https://bitinfocharts.com/comparison/bitcoin%20gold-hashrate...

That graph doesn't tell me how much it costs to launch a 50% attack. Maybe I'm just lazy, but I want a table with the name of the crypto currency in one column, and the cost in USD to launch an attack in another column.

Figuring that out sounds like a fun but non-trivial project. Since crypto currencies have different mining schemes one would need to keep track of the hash/$ ratio for each one. I guess the simplest way to do so would be to cross-reference the different mining market places that exists. Do you have other ideas for figuring out the hash/$ ratio?

Re: Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

#103

Post by mike-cardwell »

dragonwriter wrote: post #99
mike-cardwell wrote: post #84

Earlier quoted context omitted.

That graph doesn't tell me how much it costs to launch a 50% attack. Maybe I'm just lazy, but I want a table with the name of the crypto currency in one column, and the cost in USD to launch an attack in another column.

> but I want a table with the name of the crypto currency in one column, and the cost in USD to launch an attack in another column. Doesn't the cost depend on who you assume the attacker is? The required hashing power doesn't have the same acquisition and operating costs for all potential attackers.

Of course, you're correct, but that's just an implementation detail.

Each currency would need an explanation of what resources the calculation was based on. E.g, n instances of a blah node on Google Cloud Platform running software x in config y for z hours.

Re: Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

#105

Post by onecooldev24 »

drexlspivey wrote: post #98
jhpriestley wrote: post #83

When Bitcoin was running up to $20,000, I tried to analyze the system and come to a personal conclusion about its equilibrium value, because I didn't want to miss out if it really was the currency of the future. I ended up not investing, because of the possibility of a double-spend attack. I think that cryptocurrency enthusiasts are seriously underestimating the importance of double-spending attacks to the economics…

What a lot of people in the thread seem to be missing is that when you receive a huge payment you can require a higher amount of confirmations to accept it. High enough that it would make the 51% attack unprofitable.

you can split the payment to multiple small amounts.

Re: Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

#107

Post by mike-cardwell »

Zalastax wrote: post #102
mike-cardwell wrote: post #84

Earlier quoted context omitted.

That graph doesn't tell me how much it costs to launch a 50% attack. Maybe I'm just lazy, but I want a table with the name of the crypto currency in one column, and the cost in USD to launch an attack in another column.

Figuring that out sounds like a fun but non-trivial project. Since crypto currencies have different mining schemes one would need to keep track of the hash/$ ratio for each one. I guess the simplest way to do so would be to cross-reference the different mining market places that exists. Do you have other ideas for figuring out the hash/$ ratio?

Yes. It would require a bunch of up-front and on-going work to keep this website up to date. I guess that's why it doesn't exist.

Re: Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

#108

Post by Taek »

celticninja wrote: post #76
Taek wrote: post #70

Earlier quoted context omitted.

Well, under the standard assumptions of blockchains like Bitcoin, yes it's incredibly expensive to obtain enough hashing power to do a 51% attack. There's a lot of nuance to it though. In this case, Bitcoin Gold chose to have an "ASIC Resistant" algorithm, Equihash, and likely was only protected by GPUs mining the network. Bitmain has recently released an ASIC for Equihash that is substantially cheaper and more energ…

but hashrate on BTG has been falling consistently since inception, it doesnt look like someone invested in a load of ASIC devices to perform this attack, more like they kept the same operation and watched its % grow as other miners left the chain for a more profitable coin.

The hashrate charts don't measure orphaned blocks, so the attacker hashrate (manifested in the form of a bunch of orphaned honest blocks) wouldn't be visible in that chart.

Re: Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

#110

Post by tehsauce »

tlarkworthy wrote: post #92
jhpriestley wrote: post #83

When Bitcoin was running up to $20,000, I tried to analyze the system and come to a personal conclusion about its equilibrium value, because I didn't want to miss out if it really was the currency of the future. I ended up not investing, because of the possibility of a double-spend attack. I think that cryptocurrency enthusiasts are seriously underestimating the importance of double-spending attacks to the economics…

I think the argument is that by doing a 51% attack you undermine the market value so you never get the rewards. This makes sense, but only for the leading crypto coin. As we see here today, you can 51% attack smaller coins, which should imply an increase in the value of Bitcoin from consolidation.

The spooky thing that this made me realize, is that if anyone did find a vulnerability in bitcoin (or any cryptocurrency) is that they would have a greater incentive to only slowly leech off the system, because they will be able to siphon out much more over time than if everyone panics over security. The weapon is no good unless it's secret.
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