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That’s how much money you need for a Bitcoin 51% attack

HOME PAGE INSIGHTS COLUMN SO MUCH MONEY YOU NEED FOR A BITCOIN-51% ATTACK
Anyone who owns the infamous 51% of all hash power in the Bitcoin network can manipulate the network by injecting “fake” transactions in his favor. How difficult is it to carry out such an attack?

In short, the 51% attack means that more than 50% of the total computing power in the Bitcoin network can be used to infiltrate “fake” transactions by attaching them to the blockchain. Since more than 50% of the network finds these transactions correct, they are approved and attached to the blockchain. The attacker can then infiltrate many transactions that Bitcoins transfers to him from other addresses.

More details about the 51% attack can be found in our online Bitcoin trader guide

How much money does it take to get 51% of the hash power? Required Hashpower: Bitcoin Trader Review 2018 » Full Scam Check. As an example we would like to carry out a simple milkmaid calculation to find out with what amount of capital a 51% attack could be carried out. First we assume a mining performance of 2500TH/s, which comes very close to the current Bitcoin trader status.

Let us assume that the attacker has not yet connected any miners. Since he wants to gain 51%, he has to add computing power until he has the majority and the rest of the network is 49%. This means

49% = 2,500,000 TH/s (current computing power)

After the attacker has added his computing power, the total hashing power in the network is therefore (simple three-sentence):

100% = 5,102,000 TH/s, of which the attacker should have 2,602TH/s (51%).

Required miners
We are assuming an Antminer S9 here, which is quite efficient with its 14TH/s performance. For the performance of 2,602,000TH/s we need 185,857 S9 devices.

Money needed for the crypto trader (Miner)

An crypto trader Antminer S9 currently costs € 2,010. The total cost for the 185.857 devices is about 373,5 million Euro! €373,572,570 for hardware according to onlinebetrug. Electricity costs for one day (24h)
An S9 Miner consumes 1,375 watts, or 33 kWh per day. The electricity price is approx. 0.28 € per kWh.

33 kWh x 0,28 € = 9,24 € per day for a S9 Miner

For 185,867 devices this corresponds to a daily power consumption of 6,133,281 kWh x 0.28= 1,717,318 € per day for 185,857 S9 miners.

€1,717,318
Electricity costs per day (24h)

Cost of a 51% attack for one day
At a pure hardware procurement price of 373.5 million euros and electricity costs of 1.7 million euros per day, a 51% attack would cost around 375.2 million euros per day.

€375 million
Total cost of a 51% attack

Why this calculation is daring
Of course, we have simplified this calculation considerably and made many assumptions, which are not always given in reality. On the one hand, it would probably be unlikely to order more than 185,000 devices at once without increasing the hash power in the entire network. On the other hand, it is to be expected that when suddenly feeding in huge computing capacities, some miners may decide after a few days to take their devices off the grid because the difficulty has increased so much that mining is no longer profitable enough for them at this moment.

And don’t forget: It doesn’t necessarily take 51% of the hash power to perform such an attack. They are only necessary if you want to perform it with almost 100% probability. You can try it with much smaller proportions, then the probability of success is lower. Why this is so, we have explained in the article What is a 51% attack.