
51% Attack Bleeds More Than $5M from Ethereum Classic - guiambros
https://cointelegraph.com/news/51-attack-bleeds-more-than-5m-from-ethereum-classic
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marta_morena_25
Is this actually illegal? And if so, how would a court proceeding look like? I
am pretty sure especially in the US, if you have money for a good lawyer, you
can wiggle yourself out of this one pretty easily. Just imagining the jury
overseeing this... Who is even the defendant? And what is the crime?

I imagine if such a case ever goes to court its going to be very interesting,
because for the government, this should be like being stuck between a rock and
a hard place. Acknowledging this as "theft" kindof undermines their agenda to
kill off alternative currency.

There is also another dimension to it. "Double spending" conceptually seems
very similar to the government printing money, devaluing the dollar.

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sukilot
Depends where the spending went. It's fraud to agree to buy something and not
pay.

But who is selling anything for Eth?

> Acknowledging this as "theft" kind of undermines their agenda to kill off
> alternative currency.

Whose agenda?

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marta_morena_25
> Whose agenda?

Governments generally have no interest in alternate currency systems that are
not under their control, taking off. So far, crypto currency has been flying
under the radar and the ones that have broad support from financial
institutions go against the very idea of Bitcoin and Etherum, i.e. they are
not providing much of the benefit that supporters of crypto currencies are
interested in.

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xiphias2
While it's true for the central banks (that Bitcoin is the competitor of),
many of the big financial institutions are getting envious of the fees that
Coinbase charges.

Total Coinbase fees already went over Intercontinental Exchange fees in the
last cryptocurrency bubble (because of the large margins).

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londons_explore
Could one automate this 'as a service'?

Imagine a webpage with a box to paste a transaction you want reversed. It will
quote you how much it costs to undo that transaction, and if you're happy you
pay that amount.

The service would make money if multiple people wanted transactions reversed
over the same time window, since the 51% hashpower cost only has to be paid
once, even though you get paid twice.

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sgillen
Terrifying, I wonder how big of a miner community you need to stop this from
happening. How much would it cost to do this for bitcoin?

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londons_explore
It's very much 'by design' in the currency... Anyone who accepts an incoming
transaction should wait the necessary amount of blocks to verify that
transaction, and for large amounts of $$$'s, one should wait longer. The
waiting time should be _at least_ the cost of 51% of the hashpower for the
value of the transaction.

Clearly some exchanges weren't following that rule!

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setr
This doesnt make sense to me -- as I understand it, controlling 51% of the
hashing power means you can eventually undo any transaction in the system,
because you can start from any point, and mine from there. As long as you
continue to hold 51%+, you'll eventually have the longest chain, and thus the
official history. That is, there is no protection from a 51% attack, except
time and difficulty to continue the attack until success.

Waiting for a certain number of blocks is only to reduce the probability of
natural fork eliminating the transaction (by eventually outgrowing the fork
you included your transaction into) to infetesimally small.

4000 blocks is also, I think, extremely deep into the chain. As I recall,
bitcoin exchanges default to like 6 blocks before confirming?

At least, this was from my readings into bitcoin -- not sure if ethereum
changes that equation, but im fairly positive it doesnt.

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londons_explore
Hashpower is rented these days. So the question becomes 'how much hashpower
you need for _how many days '_. Which has a dollar value.

If you are verifying a transaction of a given value, you would be stupid not
to wait the dollar value of the hashpower required to reverse the transaction.
If you run a service and someone could sign up for multiple accounts, you
should take that into account too...

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AstralStorm
Unless someone actually buys a facility (or facilities)with express purpose of
making a monopoly, and does not rent it for cheap to others.

Detecting the attack or vulnerability to it is easy in smooth difficulty
increasing proof of work systems by looking for spikes in difficulty... But
waiting for too long is not acceptable.

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dirtnugget
So this will just be happening to all altcoins until they're dead. I hope.

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storedbox
Only the PoW (proof of work) ones.

