The security expert said that while PoS is “in theory” not as secure as PoW, he admits that it still has “sufficient practical security”.
While the merger with Ethereum is touted as a major upgrade to the blockchain network, its move to Proof-of-Stake would theoretically make it more vulnerable to exploitation.
Speaking to Cointelegraph, the security researcher explained that unlike proof-of-work (PoW) systems, a proof-of-stake (PoS) system informs node validators in advance of the blocks they will be validating, allowing attacks to be planned.
The security expert, who asked not to be named, is a blockchain developer and security researcher working on a layer 2 proof-of-stake blockchain.
The researcher explained that, in theory, an exploit could happen on the Ethereum blockchain after the merge if validators manage to align two consecutive blocks for verification.
If you control two consecutive blocks, you can run an exploit on block N and complete it on block N+1 without any arbitrage bot entering and fixing the price you manipulated between them.
From the point of view of economic security [this vulnerability] makes these attacks relatively easier to perform.
The expert said that while miners can also verify sequential blocks in PoW networks, this amounts to “pure luck” and does not give the miner time to plan an attack.
As a result, the security researcher argues that Ethereum will lose some security strength when the merge goes live:
How do we stand right now [with] Ethereum Proof of Work vs. Ethereum Proof of Stake, Ethereum Proof of Work Has Stronger Security […] and economic guarantees.
“But this, as they say […] proof of stake [still] has sufficient practical safety [and] never mind that theoretically it’s not as secure as proof of work. It is still a very secure system,” he added.
The security expert added that “Ethereum is working on a fix [the consecutive block issue].
This is a difficult problem to solve, but if it is done then Proof-of-Stake security will be [further] increase [as] they will be protected from these attack vectors.
There are POS discounts for Ethereum validators as the consensus rules were designed to provide validators with an economic incentive to properly validate incoming transactions, and any behavior contrary to this will result in their share of ETH being reduced.
The Ethereum merge is expected to finally happen on September 15 around 2:30 UTC, according to Blocknative’s Ethereum merge countdown. The transition to PoS should make the Ethereum network more scalable and energy efficient.