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

Hussam Abboud, the researcher cryptocurrency Brazilian FECAP University, published an article in which he demonstrated that a successful attack on the blockchain such a major cryptocurrencies like Ethereum Classic (ETC), having a market capitalization of $1.6 billion, would only cost $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 hashrate of the Ethereum network, must switch their devices to the Ethereum Classic network, where they will control 51% of the hashrate already. Accordingly, the cost of 51% attack within one day on the Ethereum Classic network for these 2.5% miners will be equivalent to the amount of awards that they will receive less, that is, about $315 000 or 525 ETH.

In his study, Abboud departs from the classical 51% attack cost model and relies on his own Rindex v2 model.0. He notes that the classical model takes into account the cost of purchasing mining equipment and electricity. However, to consider these expenses in the attack on the PoW-blackany not required, as the attacker could just rent the hash power.

According to the researcher's calculations, the cost of 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 the fix or the price falls to the levels where its further implementation becomes impractical.

Abboud notes that the developer of bitcoin, creating its consensus Protocol, based on the fact that miners will not dare to carry out such an attack, because it will negatively affect the course of the crypto currency and will ultimately be unprofitable for them, but after 9 years, this assumption has ceased to correspond to reality.

"There are large exchanges with high liquidity that allow for short sales using a leverage of 2.2 x to 100x," he writes. "The market is becoming more liquid for the opportunities you win during the price decline."
In April, Bitcoin Core developer Jimmy song published a material in which he spoke about the scenarios of mining centralization and explained why such attacks are rather a theoretical threat. However, it has recently become known about a successful spending-again attack that occurred in the bitcoin Gold fork blockchain.