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Yesterday's 51% attack on Ethereum Classic was the latest high-profile exploit of a well-known problem with smaller coins. The problem is that you can not just stop the possibility of such an attack: the system is designed to respect those who have the most control, but you can make it harder for a single attacker to take control.
And although some smaller coins, such as Horizen and Komodo, have already strengthened their defenses, it is time for everyone to learn and implement their open source secrets.
But first, to recap: to achieve 51% attack on Ethereum Classic, an opponent has managed to gain control of enough hashpower computing power, which typically miners use to create new coins. rewrite the blockchain. Blockchain works according to the majority rule, so anyone who can control most of the network can influence his event record. The irony here is that the Ethereum Classic existed because it refused to let it rewrite its blockchain after DAO hacking two years ago. However, between 5 and 7 January, the blockchain was rewritten 15 times, according to Coinbase, losing 219,500 ETCs (worth about $ 1.1 million).
As mentioned, these attacks have become increasingly common. Verge was hit three times last spring with a 51% attack, which led to the creation of 35 million XVG ahead of schedule, largely by hackers, and dropped. Other attacks include Horizen (formerly known as ZenCash), Vertcoin and Bitcoin Gold; millions of dollars of tokens have been lost.
Even the recent fork of Bitcoin Cash indicates the intrinsic problem of what happens when a party can unilaterally direct loads of hashpower into a network. Although he presumably cared about the best interest in the network, Roger Ver was able to pay the miners to make his orders.
The vulnerabilities of these networks, to the attacks of good or bad purchases, are reduced to a technical problem: if two blockchains use the same algorithm, the miners can easily move from one extraction to another. extraction of the other. And this is a problem if someone can gather – by mistake or scam – a huge hash power on a blockchain, then move it suddenly to another blockchain.
In reality, this is a way in which the attack of Ethereum Classic could be successful. Considering that it has a hasrate twenty times smaller than Ethereum, anyone with 10% hashrate of Ethereum could control it. Another possibility: the hashrate may even have been legally rented from a service like NiceHash. (Estimates of how much 51% of a blockchain attack can be found here, in addition to the available hahrate).
The key point is that blockchains that use the same algorithm as a much more popular currency – which is all too common given that many blockchains are bifurcated by the better known ones – are potentially vulnerable to a hostile takeover. And the rest could be subject to attacks in which the hacker simply rents the requested hash.
OK, so what can you do?
It is important to note that 51% attacks are a Feature-not a bug Permitting a completely decentralized currency means that it must be controllable by the masses. However, there are several ways to prevent the bad side effects of such attacks, such as rewriting the past blocks, keeping the network open.
Some coins have put in place measures to stop the 51% attacks. In June, Horizen suffered three double expenses for a total of ZEN 23,000 ($ 124,000). To do this, the attacker extracted a longer chain of blocks in secret – which excluded the three transactions – and transmitted the entire chain at once to the network, replacing the existing chain and making sure that transactions never happened.
The solution? The network has been updated to penalize miners who transmit long chains of blocks to the network. This network has been secure since that update.
Others have been even more creative. Komodo has decided to use the security of the Bitcoin blockchain as a place for backups of its blockchain. It has 64 "notarial" nodes voted by the community. These are responsible for registering a hash block from a Komodo block in the Bitcoin blockchain every ten minutes. This means that the miners can control which is the correct chain to follow, giving the attackers only ten minutes to perform a 51% attack. This level of security, known as a delayed work trial, is now being used by five other blockchains.
Several blockchains decided to upgrade their security after being subject to a 51% attack, including Verge and Horizen. In light of the latest attack, it is time for some blockchains to be more proactive. We are watching you, Dash, Metaverse and Bitcoin Private. Real money at stake
