Recent cryptocurrency news has been dominated by 51% attacks, whereby a single actor controls the majority of the mining power and is able to use this to reverse transactions. Bitcoin Gold and Verge, as well as Monacoin, recently suffered similar attacks.

This has called into question original estimates of the level of network security provided by pure proof-of-work mining. A determined and powerful actor can compromise most major cryptocurrencies with relative ease The selling point of proof-of-work models is that miners are incentivized to secure the network with their computing power, and mature networks will acquire enough hashrate from miners to effectively block all but an extremely powerful attacker from compromising the network.

However, attacking a network may prove to be easier than originally thought. 51Crypto compiled a list of proof-of-work cryptocurrencies with a projected chart of the costs to take over a majority of hashrate for an hour.

The site estimates ease of attack by finding the cost of purchasing hashrate on NiceHash for each respective coin, then estimating the total cost of attacking a network for an hour’s duration. NiceHash’s rates are used to calculate the entire hashrate’s cost, even when only a small percentage could be used from the service.

Naturally, mounting such an attack can prove more complicated than simply purchasing hashrate, as in some cases purchasing specialized hardware, which may be in limited supply, and other logistical issues may be present, but the experiment illustrates some challenges facing pure proof-of-work coins. Proof-of-stake’s centralization problem The main alternative mechanism to proof-of-work mining is proof-of-stake, which essentially limits validation of the blockchain to actors who prove control over a portion of the coin’s supply. Read more from…

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