A suggested upgrade to the Ethereum protocol would eliminate the risk of a 51% attack.
The proposal, a technical paper from founder Vitalik Buterin, would raise the number of necessary malicious nodes to 99%, meaning only 1% of nodes would need to be honest for the network to remain secure. It works by valuing observers of the network – as long as there is a 1% honest party the network would remain secure.
51% attacks have been a growing threat to many cryptocurrencies based on the Nakamoto (Bitcoin) blockchain protocol. If an attacker can control the majority of nodes (51%) then they can control the blockchain and forge transactions.
Recently there have been growing concerns that Bitcoin, the market leading digital currency could become victim to such an attack. Chinese mining company Bitmain has been amassing a staggering amount of mining power, with its two companies BTC.com and Antpool recently estimated to own over 40% of the network power.
The state of the Bitcoin network
While the number is short of the required 51%, Bitmain also allocates mining power to Bitcoin Cash, Monero and other cryptocurrencies. If the company turned all its attention to Bitcoin, commentators speculate a 51% attack could easily be within reach. Whether the company would choose such a path is not known.
51% attacks haven’t been confined to horizon threats- the Verge cryptocurrency was struck by a 51% attack in April of this year, losing 250,000 tokens. Following the loss of control developers conducted a hard-fork, reverting the blockchain to a prior state. It was a move deemed necessary to protect investors, but it did not impress those whose interest in cryptocurrency stems from decentralization.
Ethereum has been slowly transitioning towards a proof of stake model, which has advantages in defending from 51% attacks. In a proof of work model miners can attempt multiple 51% attacks, reapplying their mining hardware to new networks at will. The proof of stake model means that following an unsuccessful 51% attack all of an attackers control over the network, their stake, is lost. This increased risk to attackers is aimed to be a vital defense measure.
Vitalik’s proposed upgrade is another layer of protection for the protocol, and if it is accurate and implementable, should make 51% attacks no longer a threat to the network.
