In a highly complex paper, Ethereum’s co-founder Vitalik Buterin has proposed a new kind of consensus algorithm which requires just 1% of nodes to be “honest”.
This means, theoretically an attacker would require control on more than 99% of nodes of the Blockchain to carry out an attack. So no more 51% attack.
“Did you know that if you add even more assumptions (specifically, you require observers to also be actively watching the consensus, and not just downloading its output after the fact), you can increase fault tolerance all the way to 99%?” – Vitalik said in the paper.
The new algorithm was first invented by Leslie Lamport in 1982, who is a computer scientist who received the Turing Award for his work on distributed systems. Vitalik used Leslie’s solution in terms of the blockchain.
How it works
The new algorithm introduces a new kind of validator nodes called as the “independent observer nodes”. These nodes observe the chain in real-time and detect inconsistencies in when the message appears. This works because, Double Spend attacks are slightly quicker (or slower) compared to normal transactions, and the special nodes in Vitalik’s solution detect just that.
Ethereum developer Conrad Barski explains in a little more details on how it benefits the chain.
“Usually, all blockchain consensus[algorithms] care about is what the validators (i.e. miners) of a chain do. Vitalik is proposing that if an independent observer of the network traffic (i.e. just the blockchain client a user is running, not a miner/validator) watches what’s happening in real time and pays attention to when messages appear, they can detect ‘foul play’ by miners performing a 51% attack and this can provide additional safety guarantees that can protect against such an attack. This is similar to this is somewhat similar to how merchants are already checking for 51% attacks themselves, only Vitalik’s version is more large-scale and complex.“
Ethereum has one of the most active development community in the world of Blockchain. Currently, the Ethereum team is shifting from Proof-Of-Work (POW) based consensus to a Proof-Of-Stake (POS) based one. The exact timeline of the implementation has not been provided. It is interesting to note that once the POS based consensus is implemented on the Ethereum blockchain, the block reward will drop from 3 ETH to 0.6 ETH.
“Ethereum blockchain could become the most secure public blockchain in the world”
With the implementation of the new “observer nodes”, Ethereum blockchain could become the most secure public blockchain in the world. The timelines for such an implementation has not been given, but its safe to assume that the new algorithm will be implemented after the POS based consensus goes live.