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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

#141

Post by XR0CSWV3h3kZWg »

oh_sigh wrote: post #130
tehsauce wrote: post #110

Earlier quoted context omitted.

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.

Even finding a single double spend attack that only double-spends 1 satoshi would be enough to destroy bitcoin.

You won't really be able to process tx that low, you'll need to pay a tx fee proprtionate to the number of bytes. 1 satoshi per byte is a good rule of thumb for a very cheap tx. It takes more than 1 byte to describe one satoshi, so you can't get your tx to propagate.

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

#142

Post by bondi »

snarf21 wrote: post #124
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 one of the other issues is that each transaction that they are double spending can be worth so much. If each transaction was maxed out at say $100, the incentive to double spend the transaction becomes smaller. Obviously that changes a lot about the costs of mining and transactions, just saying the bigger a single transaction or value in a single address, the larger the likelihood of an attack. We see the sam…

This would probably lead to a huge increase in transactions, and PoW mining as of now will not to be able to process tranactions fast enough and the coin ends up clogged and unusable.

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

#143

Post by XR0CSWV3h3kZWg »

s73v3r_ wrote: post #116
XR0CSWV3h3kZWg wrote: post #6

more details here: https://forum.bitcoingold.org/t/double-spend-attack-on-excha... Bitcoin gold was a fork to try and decentralize mining. It changed to a proof of work that is supposed to be ASIC resistant. It looks like the typical situation is mining by GPU for equihash (BTG PoW). BTG hashrate is at ~30MH/s at the moment, where Zcash's hashrate is at ~486MH/s. I don't have the numbers off hand, but it'd be interes…

"It changed to a proof of work that is supposed to be ASIC resistant." These are the absolute worst. All they're doing is causing the cost of graphics cards to go up.

It's great if you own NVDA!

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

#144

Post by banachtarski »

mike-cardwell wrote: post #15
ada1981 wrote: post #7

Curious if this is illegal in anyway? I suppose there will be increasing incentive to do the numbers on the hash cost to take over a coin and to execute these attacks. Neat.

I think stealing is illegal, yes.

Sure but who regulates it :)

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

#145

Post by bo1024 »

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…

Those are some really great and interesting points. However, I think there is a resource you didn't mention that combats such attacks: time. If I'm a vendor, e.g. I pay cash for bitcoin, then I can tune the amount of time the transaction is held in limbo or escrow based on the vulnerability of the network.

For instance, I can decide not to finalize the transaction until I see a chain with 12 new blocks added after the transaction block. So an attacker has to control 51% for 2 hours to successfully scam me. Or I can make it 24 blocks (4 hours), or whatever.

Not sure this can mitigate the attacks and market forces you discuss, but it might. I see Bitcoin moving toward an intermediary system where you have a "Bitcoin balance" with a "Bitcoin bank" that allows you to make immediate transactions and takes on the risk and time delay of settling these transactions on the blockchain over the course of the next day or two.

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

#146

Post by guiomie »

XR0CSWV3h3kZWg wrote: post #6

more details here: https://forum.bitcoingold.org/t/double-spend-attack-on-excha... Bitcoin gold was a fork to try and decentralize mining. It changed to a proof of work that is supposed to be ASIC resistant. It looks like the typical situation is mining by GPU for equihash (BTG PoW). BTG hashrate is at ~30MH/s at the moment, where Zcash's hashrate is at ~486MH/s. I don't have the numbers off hand, but it'd be interes…

I run around 630 sol/s per 1080ti GPUs, each costed me around 950$. You'd also need to add the electricity in there, I think the challenge is to control an infrastructure being able to do over 15 MH/s as opposed to having the capital.

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

#147

Post by sanxiyn »

zeth___ wrote: post #104

Purely hypothetical and mostly stupid: could double spending attacks be a way to overcome the issue of a limited supply of coins and the fact the total number of coins tends to zero as old coins are lost?

No, because transactions are reversed in double spend attacks. It does not increase the supply.

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

#148

Post by zaroth »

So this would require an attacker to pay into the exchange with BTCg, have the deposit clear and approve for trading, trade it for another currency, and have that trade settle and be clear for withdrawal, and then process the withdrawal, all in under 4 hours. After which point the attacking miner surfaces a longer chain they had been keeping which doesn’t include the original BTCg deposit.

Alternatively, if the exchange isn’t smart enough to pay short-term withdrawals with inputs that link back to the recent deposit, an attacker could just deposit and then withdraw with no trade and the withdraw transaction is valid even if the deposit is double-spent.

An exchange that lets a trader deposit millions in one crypto-asset, exchange it for another, and clear a withdrawl in 4 hours... got what was coming to them? Where’s the KYC process for a million-dollar deposit?

There’s a reason new deposits in a brokerage account take a few days to settle / be cleared for trading. And again after selling before funds can be withdrawn. And that’s a currency where most transactions can be reversed!

It would be one thing to allow 10 block settlement for Bitcoin main-net. It’s another to allow it with a thinly mined alt-coin.

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

#149

Post by rpearl »

cachvico wrote: post #23
jacquesc wrote: post #17

Earlier quoted context omitted.

So it's not a complete waste of natural resources because it helps secure "the chain"?

Exactly. We should stop using the word "waste" to describe the energy consumption of the Bitcoin miners. It's not waste if it serves a purpose. The service it provides is to guarantee the integrity of the blockchain without the requirement of a central authority.

it is a waste. Bitcoin is an unqualified environmental catastrophe that is literally erasing any progress we've made to combat climate change. Burning away the future, turning useful energy purely and directly into waste and profit by shouting numbers into the void, not even leaving any artifact of value in its wake.

There's not anything wrong with having a central monetary authority. There's not anything wrong with having institutional trust.

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

#150

Post by always_good »

spookthesunset wrote: post #50
drexlspivey wrote: post #34

Earlier quoted context omitted.

Would you ask the same question if the world run 100% on renewables? If not, it seems that your argument should be "we should accelerate our transition to renewables" instead of "bitcoin spends too much power". Also they pay for all the energy they spend so what exactly is the problem? Do you see vegans complain for the resources spent to raise animals?

> Would you ask the same question if the world run 100% on renewables Opportunity cost. All that 100% renewable energy could be used for something that actually adds value to society but isn't because it is being pissed away on the Rube Goldberg invention known as Satoshi's BlockChain. > Also they pay for all the energy they spend so what exactly is the problem? Give me a fucking break. These miners raise the price o…

Pretty weak line of reasoning.

How much energy do you and everyone else waste doing things that don't add value to my life or society?

Using your own comparison, why is it a big deal if little Jimmy can't afford a graphics card to play some Counter-Strike? Is gaming a better use for energy?

Seems weird to pick on cryptocurrencies if you actually believe your premise, which I don't think you do.

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