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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

#151

Post by bo1024 »

onecooldev24 wrote: post #133
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…

can you explain this in better words: "then it would always make sense to rent 51% of the capacity at market rates, earn the transaction fees, and also perform a double-spending attack."

I think what jhpriestly is saying is: As the market gets efficient, the price of renting mining capacity will approach the profits earned from transaction fees. So renting mining capacity will almost pay for itself, i.e. is almost free. But then you might as well rent a lot of it, like 51%, because it's allowing you to attack the chain almost for free.

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

#154

Post by Arbalest »

verbatim wrote: post #129
mike-cardwell wrote: post #12

Crypto currencies are worthless unless they have an enormous amount of hashing power behind them. We could really do with a webpage with a list of crypto currencies, the hashing power currently behind them, and how much it would cost somebody to take over 50% of the network. Or does that already exist?

> Crypto currencies are worthless unless they have an enormous amount of hashing power behind them. I think this is only true if you assume that crypto-currencies must be based on proof-of-work algorithms. What about proof of stake systems?

Someone has already asked that, and the response was, such systems are still theoretical without a working proof of concept.

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

#155

Post by thaumasiotes »

bo1024 wrote: post #145
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 th…

> 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.

How would this system differ from an ordinary bank in the system we have now?

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

#156

Post by spookthesunset »

always_good wrote: post #150
spookthesunset wrote: post #50

Earlier quoted context omitted.

> 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.

> Pretty weak line of reasoning.

Hardly. What, exactly, does bitcoin add to our world? Near as I can tell it's only use case is Making Money Fast (for the folks at the top of the pyramid, anyway) and scamming the bejesus out of all the rubes who fall for the con.

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

Bitcoin is estimated to consume more than 0.5% of all the worlds energy. Many nations use less power than bitcoin consumes. Bitcoin can process a mere 4 transactions per second. Please go on and explain to me why this is even a remotely acceptable thing.

The whole space is a deplorable shame and people like you should be absolutely ashamed of yourselves. You are a drain on the planet's limited resources.

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

#157

Post by CydeWeys »

thaumasiotes wrote: post #155
bo1024 wrote: post #145

Earlier quoted context omitted.

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 th…

> 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. How would this system differ from an ordinary bank in the system we have now?

It's still trustless, decentralized, yadda yadda.

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

#158

Post by andirk »

ryanwaggoner wrote: post #109

If Bitcoin became the dominant currency of humanity, eventually we’d darken the galaxy by building Dyson shells in the ultimate energy arms race to prevent a 51% attack. Joking. Mostly.

A 51% attack, like you're saying, only needs more than half of the hashing power and that's it, and the whole thing is blown. But then again, all you need is 51% more weapons than your enemy and you can probably beat them too.

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

#159

Post by dlubarov »

celticninja wrote: post #69
jsutton wrote: post #61

Earlier quoted context omitted.

Not necessarily, non-hashing consensus seems to be where most blockchain projects are going. So these would require a stake of assets or similar, instead of wasting computing cycles.

Proof-of-Stake(POS) is still theoretical at this stage, there is no working solution or proof-of-concept. It is a nice(ish) idea to reduce the energy consumption of blockchains but isnt really a solution to decentralisation.

There are some working solutions now, like NEO, Dash, and NXT. Ethereum is sure to adopt it as well; a lot of details are TBD but there's little question that the community will adopt some form of PoS.

I'm not saying it's perfect -- there are some downsides like needing a cap on fork distance in order to prevent stake bleeding attacks [1] -- but it's certainly viable.

[1] https://eprint.iacr.org/2018/248.pdf

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

#160

Post by CydeWeys »

onecooldev24 wrote: post #135
mehrdadn wrote: post #126

Earlier quoted context omitted.

Confused... I thought the claim was about receiving and not sending?

if multiple accounts send multiple small payments (controlled by the same guy), then the exchange wont wait as long for the confirmations.

The exchange can have thresholds for total volume per given time interval then. Once the total amount of pending transactions breaches a given volume, the transaction period for more transactions within the window goes up.
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