Quote from: odolvlobo on Today at 05:33:50 PM

Quote from: DooMAD on Today at 05:26:17 PM

The financial consequences of orchestrating such an attack outweigh any potential gains that could be made.

That is not necessarily the case. There have been several 51% attacks against certain altcoins that resulted in financial gains by the attackers. Furthermore, these attacks did not result in the death of the coins.

You're both right. However, since the topic directly implies a 51 % attack on the Bitcoin network, I'll have to side with DoomMAD on the subject of being an attack that would involve a massive amount of funding (and equipment) just to be able to pull it off. DannyHamilton described the process in a very simple way some time ago:

Quote from: DannyHamilton on January 24, 2020, 05:56:52 PM

Quote from: Euro1000 on January 23, 2020, 08:36:32 PM

Following scenario: A government would like to destroy Bitcoin. It buys a significant number of ASICs to build up a huge mining farm and carries out a 51% attack.

"A significant number"?

They would need to purchase more hashpower than the entire rest of the Bitcoin mining world combined.

The current global hash rate is approximately 120,000,000,000,000,000,000 hashes per second (120 eH/s).

That means that the attacker would need to purchase enough equipment to generate more than 120,000,000,000,000,000,000 hashes per second, and they'd have to do that quickly, since the global hash rate that they are trying to overcome is currently still increasing. If it took them too long to purchase all their hash power, the global hash rate may have increased, and they'd still need to purchase even more.

The Antminer S17 calculates approximately 67 TH/s and costs $1600 to purchase.

The attacker is going to need to purchase:
120,000,000,000,000,000,000 / 67,000,000,000,000 = 1,791,045 Antminer S17

I'm not sure how long it would take Antminer to manufacture 1.8 million S17 units, but let's pretend they just happen to have them sitting in a warehouse waiting to be sold...

That's going to cost the attacker $2,865,672,000

So, they are going to spend nearly 3 Billion dollars just to acquire the equipment. Then they are going to need to have somewhere to store/operate all this equipment. They'll need to pay some people to set up and maintain everything. They'll also need about 5.8 gigawatts to power the mining equipment (plus the electricity need to cool it all and light the buildings that house it all.

This is almost certainly going to create a noticeable shortage of Antminer S17 units, which will drive up the costs of whatever mining equipment anyone can get their hands on.

After all that money, and all that effort, it's still questionable whether they'd actually "destroy" Bitcoin. First of all, they won't be able to chnage any of the consensus rules. The best they'd be able to do is block transactions from being confirmed, keep any other miners from earning any revenue, and/or perform a double-spend (assuming they can find anyone that is willing to engage in a transaction with them). There is a small chance that an overwhelming majority of users of Bitcoin might decide to fork the code such that all the mining power the attacker purchased could become instantly worthlesss.

Perhaps it would be better/cheaper to just create a law (with penalty of death) that makes it illegal to mine, purchase, sell, hold, or transact with Bitcoin? Then send a few missles at large mining operations in other countries? That should significantly reduce participation. Then once the hash rate drops down below 67 TH/s, they can perform their 51% attack with a single Antminer S17!

Do consider that the current hash rate sits around 204,733,000,000,000,000,000 hashes per second ( ~ 204.733 EH/s[1] ). Adjusting the calculations made by DannyHamilton we get :

Equipment: Antminer S19 Pro (110TH/s)[2] / Price: $5,940[3]
Nº of antminers: 204,733,000,000,000,000,000 / 110,000,000,000,000 = ~1,861,210
Antminer cost: $11,055,582,000
Needed power: ~6.0 GW

Considering the current chip crisis and current world events, I highlt doubt that such operator would be able to grab his hands on such a large quantity of equipment (considering that he/she manages to get warehouse big enough to house the infrastructure needed). In the scenario that all the resources problems get solved (and a huge amount of money is spent) the attacker would also be burning money while sustaining the attack (if the transaction is deep within the blockchain, he/she would need to spend a lot of time and energy to reverse it). Furthermore the current distribution of hash rate is the following one[4]:

Foundry USA, a subsidiary of Digital Consulting Group (DCG), and Binance Pool have combined hash rate of ~ 43 % which means that they'll need to "partner" with some other group in order to make this happen - which they won't because it goes directly against their "business" and they are also companies that can be easily scrutinized by the general audience making this event even more unlikely to happen...

[1]https://www.blockchain.com/charts/hash-rate
[2]https://www.asicminervalue.com/miners/bitmain/antminer-s19-pro-110th
[3]https://shop.bitmain.com/product/detail?pid=00020220616112636834T0C1ADTd062A
[4]https://dcg.co/