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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

#381

Post by cal5k »

biztos wrote: post #211
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'm a bit ignorant about cryptocurrency, but doesn't "I pay cash for bitcoin" sort of prove the parent's point that it's not "the currency of the future?"

Sort of like how you pay USD for Euros when you’re on vacation?

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

#382

Post by thedailymail »

IkmoIkmo wrote: post #358
thedailymail wrote: post #340

If all that is required to reverse transactions is 51% control, cannot the transactions that occurred during the double spend attack also be reversed by a 51% coalition once the attacker loses its majority?

Sure but it doesn't solve anything. Remember that people do not trade token A for token A. You don't buy dollars with dollars. You use dollars to buy something else, like euros. So you may reverse one token, but you won't be able to reverse the other. i.e. suppose you have $100 and I have 100 tokens (e.g. bitcoin gold coins). You pay me $100 and I give you the coins. I now double-spend and sell the coins to someone e…

Thanks for the clear and detailed explanation!

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

#383

Post by nicky0 »

wpietri wrote: post #343
beager wrote: post #301

Earlier quoted context omitted.

My assessment is that the greatest vulnerability in Bitcoin is its breathless supporters, who will look past the dynamics of Bitcoin in adoration of the mechanics of Bitcoin. To that end, larger, more sophisticated enterprises (banks, hedge funds, etc) are likely leeching slowly off the system, propping the price up and inflating it when they can, so they can extract as much value as possible out of its correction to…

I think the split you draw between people looking at Bitcoin-the-real-thing and people adoring the machinery is an excellent one. If you look at the original paper, it's pretty clear that Bitcoin was meant to be peer-to-peer electronic cash: https://bitcoin.org/bitcoin.pdf In practice, it has failed at this aim. I don't think that was necessarily so; plenty of things start out rough and become more useful over time.…

How would you change the machinery?

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

#384

Post by nicky0 »

brownbat wrote: post #318
jjeaff wrote: post #266

Earlier quoted context omitted.

That's not buying anything with Bitcoin. You are converting your Bitcoin to USD and then purchasing using the traditional, centrally controlled financial system. And that's not even considering the transactions fees it costs to get the Bitcoin to your account. Then there are the transaction fees for using the card, which coinbase says is free "for now".

That's like saying you can't buy anything with a VISA. Sure, transactions are intermediated through some consensus denomination for exchange. So? He still lost bitcoin and gained tacos. Just as someone else might lose a portion of a credit balance and gain tacos. You get just as full either way.

Was there an individual bitcoin transaction for each purchase? No, he just paid his credit card bill with bitcoin.

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

#385

Post by nicky0 »

stale2002 wrote: post #249
apo wrote: post #216

Oddly enough, one of the selling points of Bitcoin Gold (a hard fork of Bitcoin) was its use of Equihash instead of SHA-256. The idea was that a memory-hard proof-of-work function would inoculate Bitcoin Gold from miner centralization. The problem with mining centralization is that sufficiently powerful miners can attack the network by rewriting blocks. This opens the door to double spending. This was exactly the att…

All of the major Bitcoin miners are very pro Bitcoin cash. They basically created Bitcoin cash. They would be more likely to attack Bitcoin Core, if anything. I would also point out that Bitcoin cash is the 4th largest crypto currency in the world, by market cap. If IT is in danger.... Well I fear for everyone else even more.

Bitcoin Cash is only protected by the benevolence of the large miners. It is otherwise wide open to a 51% attack.

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

#386

Post by PeterisP »

bb88 wrote: post #364
bo1024 wrote: post #151

Earlier quoted context omitted.

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.

I think a good question is, is there a market for renting asic mining gear? Yes, but only if mining the coins via renting is cheaper than buying them outright. If you're a miner, it makes sense to rent out your gear, because you get a guaranteed payment higher than you could make via mining.

I've heard an opinion (but I'm not certain) that mined coins are considered less traceable than purchased coins.

For any purchase, there's a trail that leads to you through however you paid for it; for mining, the mined coins are totally disconnected from the hardware that mined the block and how you bought it.

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

#387

Post by dnautics »

wpietri wrote: post #343
beager wrote: post #301

Earlier quoted context omitted.

My assessment is that the greatest vulnerability in Bitcoin is its breathless supporters, who will look past the dynamics of Bitcoin in adoration of the mechanics of Bitcoin. To that end, larger, more sophisticated enterprises (banks, hedge funds, etc) are likely leeching slowly off the system, propping the price up and inflating it when they can, so they can extract as much value as possible out of its correction to…

I think the split you draw between people looking at Bitcoin-the-real-thing and people adoring the machinery is an excellent one. If you look at the original paper, it's pretty clear that Bitcoin was meant to be peer-to-peer electronic cash: https://bitcoin.org/bitcoin.pdf In practice, it has failed at this aim. I don't think that was necessarily so; plenty of things start out rough and become more useful over time.…

In practice, Airbnb has failed at its aim of providing airbed style accommodations for conference goers.

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

#388

Post by jacobush »

hossbeast wrote: post #311
mortdeus wrote: post #238

Earlier quoted context omitted.

What about state level actors, say the NSA, that consider bitcoin supplanting the US dollar as the standard medium of international currency exchange a huge threat to the world economy? (or at least their ability to control it) I think people need to be concerned that Governments, at any point of time, with their incomprehensibly huge computation power, can use it to crush bitcoin. Not only that but they can pass law…

How is the government going to forcibly size a wallet? Are you suggesting they can break the crypto, or that they will compel people to divulge their keys?

"Today in an emergency bill, Congress made it an act of treason to move funds from bitcoin address 1BLABLABLAh555"

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

#389

Post by Erlich_Bachman »

rvense wrote: post #380
erikpukinskis wrote: post #369

Earlier quoted context omitted.

What’s the difference between dynamics and mechanics?

The mechanics would be the internal workings, a tamper-proof shared ledger. It's so amazing! Think of all the possibilities! Then it hits the real world, and suddenly what people actually do with it and its valuation is dependent on how the exchanges operate (are exchanges even mentioned in the original paper?), energy prices in China, media coverage, interactions with alt-coins, etc.

You seem to assume that the greatest feat of Bitcoin is it's price. Yes, sure the price might be affected (somewhat) by how exchanges operate and media covers. However, many people don't care too much about the monetary price, and play the long game. In the long run, the market always adjusts. In in the end, it is the same with any other commodity or currency.

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

#390

Post by zaarn »

api wrote: post #52
jacquesc wrote: post #17

Earlier quoted context omitted.

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

How much energy is spent securing conventional financial systems? You have to include everything: banks, minting, enforcement, physical security, even military and intelligence action.

I've once worked out the CO2 output of Ethereum, which I think can be nicely worked over. Ethereum uses 191'000 people-equivalent CO2/year (1 PECO2 = 9 tons of CO2) or roughly 4 TWh per year (I'm using numbers from multiple sources and past comments from me, I apologize if it's not lining up perfectly)

The average state employes about 300'000 people (324'000) to be exact (about 16 million in total, which includes teachers and similar).

So already the Ethereum network uses half of an entire average US state to just secure it's network. The US state in question does a lot more and it includes education and similar.

Bitcoin uses 68 TWh anually, about 17 times as much or about 8.5 average US states. To secure 200'000 TX per day. In contrast the US employees handle the entire state affairs, including taxes, education, etc. for 54 million people every day.

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