Bitcoin Gold Hit by Double Spend Attack, Exchanges Lose Millions

Post by hinkley » Thu, May 24, 2018, 4:35 PM UTC

Rodyland wrote: post #240

hinkley wrote: post #233

Earlier quoted context omitted.

Not every distributed consensus algorithm is happy with 51%. If you increased the minimum to 60% you’d increase the number of machines the attacker requires by 50%. If 100 machines play fair, >50% requires 101 evil machines, but >60% requires 151 evil machines.

I think you're misunderstanding the meaning behind a 51% attack? An honest network participant will accept the chain with the largest accumulated proof of work. This is necessary to resolve forks of the chain, which are a natural occurrence. A 51% attack means that the attacker can create a chain with more work than the rest of the network. The idea that you can say "we require 60%" makes no sense by itself - you hav…

Post by Obi_Juan_Kenobi » Thu, May 24, 2018, 4:56 PM UTC

cdetrio wrote: post #294

drexlspivey wrote: post #98

Earlier quoted context omitted.

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.

Requiring more confirmations decreases the probability that a transaction will be reverted, under the assumption that an attacker has < 49% of the hashpower. If you attempt an attack with 49%, then you have a fair chance of mining, say, 6 blocks before the rest of the network. If you get unlucky then you sacrifice those rewards. But if you mine with 51% then your attack chain is (probabilistically) guaranteed to even…

Post by tacon » Thu, May 24, 2018, 5:05 PM UTC

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…

Post by wpietri » Thu, May 24, 2018, 6:27 PM UTC

conanbatt wrote: post #516

wpietri wrote: post #505

Earlier quoted context omitted.

They mainly provide addiction. Go to a casino sometime and look around. Do those people look like they're entertained? The slot machine zombies barely look human anymore. You're also wrong about taxes. Consider my local taqueria. They buy raw materials and create value by making ready-to-eat food just when people are hungry. They receive cash in exchange, a portion of which they pay in taxes to fund the infrastructur…

I dont think you've followed through on that model of yours. If you buy 50 dollars of taco materials, then taco materials seller makes likes than 50 dollars ,because the state will charge a tax on him. If he didnt sell 50 dollars worth of raw materials, he would have 50 dollars of raw materials to consume, instead of less than 50 dollars. On the other side, making the taco, you have the same issue: if you sell 100 do…

Post by bb88 » Thu, May 24, 2018, 9:07 PM UTC

brandonsometig wrote: post #425

bb88 wrote: post #351

Earlier quoted context omitted.

> I think the argument is that by doing a 51% attack you undermine the market value so you never get the rewards. Only if you make it public. A 51% attack works at a poker table too, but only if the marks don't know the game is rigged. A successful double spend makes it public, as well as announcing your intentions to get to 51%. If you're quiet and can pull off a successful 51%, you can create the double spend befor…

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.