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Cost of a 51% attack for different cryptocurrencies?

crypto51.app

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Re: Cost of a 51% attack for different cryptocurrencies?

#131

Post by hinkley »

RL_Quine wrote: post #130
hinkley wrote: post #129

Earlier quoted context omitted.

> If you report the pool's hash rate as lower err, right. If you want to convince people they're getting a fair share, you have to downplay their contributions, and since they know what they did you have to make the pool bigger, not smaller. How long would it take to notice someone was fluffing the pool by 10%?

The variance month to month is far higher than that for most pools. Nobody would ever notice, trust me.

Yeah that’s what I meant by the statistical comment.

My hardest class in college was statistics, and mostly I learned that humans suck at them.

I was binging math videos recently and I got to one where one guy made a list of “random” heads or tails, and then the other guy guessed them and got like 60% right. He was disappointed because he often does better.

Humans, he asserted, will never write more than 3 (or was it 4?) heads in a row because they feel they aren’t random enough. And because if this, over half of the possible patterns are never seen.

Which is also why, when a test that’s failing 10% of the time, my coworker who thinks he just fixed it will run the new version five, ten times and claim victory... only for it to fail four times in a row the next day.

Re: Cost of a 51% attack for different cryptocurrencies?

#132

Post by DoctorOetker »

SilasX wrote: post #101
RL_Quine wrote: post #84

Earlier quoted context omitted.

All miners connect to pools using a protocol called stratum. This is JSON piped over TCP with newline terminations. There is no authentication for this protocol and no encryption. You can simply intercept the communication here and have all the miners on a pool actually mine for your replacement pool, and nobody will ever catch on until its far too late. > If you mean the traffic of mining pools communicating their s…

Okay I see what you mean about replacing the work assignments going to the miners -- if you could tell them to solve a different block/fingerprint (hash of new block + previous block) and receive their output, then you can steal their hashing power. But I'm still not sure what you mean here: >>If you mean the traffic of mining pools communicating their solutions to the pool's "mother brain", those are already cryptog…

(I am not informed about what the typical arrangement is to spread out the stochastic reward a pool earns over its members, so I am making no claims on this front)

But if the (non-principled) value of mining 20 blocks is 20 block rewards, then there we have the cost of buying 20 blocks (assuming miners non-ideologically sell out).

Assume they would not voluntarily sell out, then any flaw in the pooling mechanism (by which miners dilute the rewards into a steady income) which allows 1) other work to be assigned to the miner 2) while still receiving their intended addresses, would allow an attacker who is able to hijack the work assignments, to buy those 20 blocks for the price roughly on the order of ~ 20 block rewards, by 1) hijacking the work assignments 2) payout out the miners the correct expected amounts so that they hopefully don't notice

Is that correct?

Re: Cost of a 51% attack for different cryptocurrencies?

#134

Post by Rodyland »

labawi wrote: post #117
AgentME wrote: post #116

Earlier quoted context omitted.

If you had 1/4 the hash power, it's true that you have 1/4 chance of creating a block before anyone else, but to be clear, doing that once isn't enough to do a double-spend attack of a transaction with some N confirmations (usually people would aim for N=6). There's only a 2% chance an individual attempt would pull that off for 6 confirmations in a row when using 1/4 the global hash power, and the whole time you're a…

If you add opportunity cost and renting cost, you are double counting. Assuming you can repeat your "totally legit" setup transactions until you succeed, with minimal cost other than rent, you would need to take more than either the opportunity cost (otherwise it's better to just mine), or the renting cost (otherwise you're still losing money).

Adding opportunity cost and renting cost isn't double counting.

Opportunity cost is the foregone block rewards that you lose because you didn't submit your blocks, because you were holding them hoping to build a long enough chain to double spend. When you fail, that reward that you would have earned is gone forever.

Renting cost is the actual $ outlay that it costs you to rent the hash power necessary to perform the attack.

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