A 51% attack on the Ethereum Classic network will cost $ 1.5 million.

Husam Abboud, a cryptocurrency researcher at the Brazilian University of FECAP, published a material in which he demonstrated that a successful attack on the blockchain of such a large cryptocurrency as Ethereum Classic (ETC), which has a capitalization of $ 1.6 billion, would be worth only $ 1.5 million. $ 55 million will be enough to completely bankrupt the cryptocurrency, along the way earning $ 1 billion, he writes.

The researcher notes that miners who control only 2.5% of the hash rate of the Ethereum network must switch their devices to the Ethereum Classic network, where they will control 51% of the hash power. Accordingly, the cost of a 51% attack within one day on the Ethereum Classic network for these 2.5% of miners will be equivalent to the amount of rewards that they will not receive, that is, it will be about $ 315,000 or 525 ETH.

In his research, Abbaud departs from the classic 51% attack cost model and relies on his own Rindex v2.0 model. He notes that the classic model takes into account the cost of purchasing mining equipment and electricity. However, it is not necessary to take these cost items into account when attacking PoW blockchains, since an attacker can simply rent hashpower.

According to the researcher's calculations, the cost of a 51% attack on the Bitcoin Cash blockchain will be 250 bitcoins ($ 1,875,000) per day, and on the Bitcoin Gold blockchain - only 26 bitcoins ($ 200,000). The attack can continue until the developers release a fix or the price drops to levels where its further implementation becomes impractical.

Abbaud notes that the Bitcoin developer, creating his consensus protocol, proceeded from the fact that miners would not dare to carry out such an attack, because it would negatively affect the cryptocurrency rate and ultimately turn out to be unprofitable for them, but after 9 years this assumption ceased to be true ...

“There are large exchanges with great liquidity that allow short selling on leverage from 2.2x to 100x,” he writes. "The market is becoming more liquid for the opportunities that you can use to win during a price decline."

In April, Bitcoin Core developer Jimmy Song published a material in which he talked about scenarios for centralizing mining and explained why such attacks are more of a theoretical threat. However, it has recently become known of a successful re-spend attack that took place on the blockchain of the Bitcoin Gold fork.