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Comment by sillysaurus3 | Hacker News Reader

One way to destroy Bitcoin would be to convince governments to launch a 51% attack against it.

An organized, worldwide campaign against BTC, complete with double-spends, would flatten the price.

I wonder if it's still feasible? Eventually it will be too hard to mine, but perhaps not yet.

A benefit of this attack is that once executed, other miners will switch away from BTC. Meaning BTC won't be able to spring up again: no one will be able to get more than the ~90% hash rate the government controls.

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16,946,489 terrahashes per second right now for the BTC network. According to some website I found you can get an ASIC that does 4.73 Terrahashes for $500. That means you'd need 17638182 TH/s at least to get 51% hashpower. That means you'd have to buy 3,729,003 of those $500 miners which would cost $1,864,501,313.80. Let's double that and call it 3.6 billion for facilities and energy costs. So yes, totally possible for a government to create a cluster with 51% of network power if they chose to. I imagine there would be pushback against spending billions to destroy people'a assets though.

Also in such a situation, consensus could be reached easily on doing a hard fork. Government's effort would go waste on the original one. They can repeat, but it will take some time, and the hard fork can happen again, until govt gives up.

A better approach by any government could be to declare it as illegal (just like drugs). By doing so, they can't eliminate it, but just curtail demand.

They could certainly cause a lot of trouble, but rather than continuously hard forking I bet people would just add hashing power to the network like crazy. It's basically the government vs everyone in the world. If the value of BTC was threatened, I'm sure a lot of hash power could get added into the network. Can the US government outspend and outpace everyone else in the world teamed up against them? It would be challenging logistically for sure, even if you had the money.

Do you think miners can switch faster to the hardfork than the government? The government can just redirect their entire mining pool at once to a new hardfork wheras miners are independent and convincing them to switch will take time.

also worst damage such a government could do would be to double-spend some coins. That is if the 51% is somehow undetected and that the rest of the bitcoin community doesn't fork the chain upon detecting such an attack.

.. but why? Why not just go after the exchanges?

https://bisq.network/

Won't work. They'll just migrate to countries without financial controls. (BTC-e et al.)

Cool story bro, but most governments would consider that a win -- it pushes the whole thing out of the mainstream.

(edit: A win if the goal was to ban cryptocurrencies.)

You know BTC-e no longer exists and was replaced by a clone called wex, which is linked to a domain in a five eyes jurisdiction (new Zealand), right?

Exchanges are a de facto part of every cryptocurrency protocol, you cannot avoid exposure to their downside risk even if you never put a single coin on any of them.

A lot of crypto fans would say you could avoid the exposure once all commerce is conducted without conversion to fiat. To include wages.

Doesn't the FBI already own one of the largest wallets after seizing Silk Roak assets?

Bulgaria has a 3 billion wallet. What's the reason then to attack bitcoin.

http://www.zerohedge.com/news/2017-12-08/bulgaria-government...

They should sell those.

And? It doesn't matters how many coins you've got to perform a 51% attack, only thing that matters is how many hashes you can perform per second.

I think they’re asking: why destroy value of an asset that they currently hold/own?

Well, it's a relatively small sum. And if it grows into a large and valuable asset relative to the government's budget, that's a bad sign: it means the government-backed dollar is losing steam relative to crypto.

It's in the government's interest to lop off the head of its biggest existential threat.

Also, Satoshi presumably passed his coins to his heirs. Who controls 6% of all wealth? I wonder.

They were rushing to sell it a few weeks ago, hopefully they managed before the decline

Yes, but that simply raises the price and encourages BTC adoption.

Governments will need to become active miners to destroy it. And unlike miners, they won't care whether they can mine faster than everybody else. Their objective is to ruin BTC.

Can someone please explain how exactly a 51% attack would actually cause double-spends to be accepted?

All the miners do is accept transactions into a block. We don't trust any given machine to validate that there were no double-spends. For that, each client would have to check the entire history before accepting payment. So, how would mining the blocks cause double spending to take place?

Don't bitcoin miners have to SIGN their blocks? If so, then broadcasting two different histories would quickly be discovered.

I guess the only thing they can do is make a bitcoin fork, something that is possible anyway, by enough miners agreeing.

Perhaps they can alternate the two forks length growth, making the clients thrash and re download the two forks over and over.

https://notehub.org/nz8d0

Basically, the longest chain is considered correct. And it has to work that way. It's why BTC is sybil-resistant.

So the attack is to get >51% of the hash power together, then mine in secret, creating a perfectly valid longer chain with a different tx history.

Publish it, and watch the world burn.

I wonder what would be needed to gain 51% hash power? How many super computers would that be?

>How many super computers would that be?

you're asking the wrong question. mainly because bitcoin mining is done with ASICs and not general purpose computers. I would be surprised if the bitcoin network hashrate isn't higher than all the general purpose computing power in the world combined (converted to double SHA256 hash rate).

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