According to CoinMetrics, an attack on Bitcoin could cost $5 billion to $20 billion, while an attack on Ethereum would cost more than $34 billion.
A 51% attack occurs when a single network miner or group of miners controls more than half of the hash rate of a blockchain network. In theory, this would allow an attacker to block transactions from occurring in the blockchain, change the order of new transactions, and potentially recover past transactions by tampering with blockchain data (known as "double spending").
However, a recent study shows that it is not economically feasible to perform such an attack under the current security setup of Bitcoin and Ethereum.
Attacking Bitcoin and Ethereum is not worth it
Referring to December 31, 2023, considering that the Ethereum price is $2,279, the total amount of pledged ETH is 28.8 million ETH, and the number of validators is 899,840 validators, CoinMetrics calculations show that the attacker would need approximately $34.39 billion to execute 34% attacks on the network.
If the attack begins on December 31, 2023, the attacker would need to breach the 33% threshold by June 14, 2024, to gain control of the network.
Attacking Bitcoin has proven equally far-fetched. Researchers estimate that attackers would face more than $20 billion in production costs as they would need to produce nearly 40 million S9 units.
Using the most powerful ASICs available, such as the upcoming Bitmain S21, will cost around $5.6 billion by December 2023, roughly a quarter of what it would cost to use the S9. This estimate is based on a unit cost of $2,240 and a production volume of 2.5 million machines.
While more cost-effective than "naive" methods, the study asserts that manufacturing at this efficiency and scale requires collaboration with manufacturers. However, attackers may encounter supply chain issues and potential retaliation.
“Our results show that the current security posture of Bitcoin and Ethereum makes attacks economically infeasible and provide empirical evidence for Nash equilibria in these networks.”
The study concluded that security measures in Bitcoin and Ethereum have reached a level where the costs and dangers associated with 51% attacks far outweigh the potential benefits. It shows that hostile behavior becomes less attractive compared to alternative strategies such as honest participation in the network or avoidance of attacks.
51% of attack risks exceed leading blockchains
This assessment may be true for top blockchains such as Bitcoin and Ethereum, but the same cannot be said for many other networks that have emerged over the past decade.
Bitcoin SV, the blockchain spun off from Bitcoin Cash and largely championed by entrepreneurs Calvin Ayre and Craig Wright, experienced three 51% losses in 2021 attack. Likewise, the little-known privacy-focused cryptocurrency Firo, formerly known as Zcoin, faces a similar test. Even Ethereum Classic is not immune to rogue behavior. #51%攻击 #比特币
