Ethereum founder Vitalik Buterin said he supports the concept of a multi-chain ecosystem, but is “pessimistic” about cross-chain bridges. According to him, the latter are vulnerable to attacks like 51%.
My argument for why the future will be * multi-chain *, but it will not be * cross-chain *: there are fundamental limits to the security of bridges that hop across multiple “zones of sovereignty”. From https://t.co/3g1GUvuA3A: pic.twitter.com/tEYz8vb59b
– vitalik.eth (@VitalikButerin) January 7, 2022
“Fundamental bridge security constraints are the key reason why I am optimistic about the multi-chain ecosystem of the blockchain (indeed, there are several separate communities with different values, and it is better for them to exist separately than to fight for influence), but I am pessimistic about cross-chain. applications, ”he wrote on Reddit.
According to Buterin, cross-chain bridges are more vulnerable to attacks such as 51% compared to tier 1 networks. He explained that even if an attacker manages to seize most of the blockchain’s power, he will not be able to take away their cryptocurrency from users, since this would “violate the rules of the protocol.”
The Ethereum founder added that a 51% attack is capable of censoring or reverting a decentralized application for a certain amount of time, but then the network will return to a “consistent state.”
“If you had 100 ETH but sold it for 320,000 DAI on Uniswap, even after attacking the blockchain in some crazy way, you will get a reasonable result – you either keep your 100 ETH or get 320,000 DAI. The outcome, in which you do not get either one or the other (or, for that matter, the third), violates the rules of the protocol, and therefore will not be accepted, “Buterin said.
He stressed that cross-chain bridges do not provide such guarantees, which means that users may lose funds. As an example, he cited the situation with the hypothetical Ethereum-Solana bridge:
- the attacker invests a large amount of his own funds in the wrapped ETH on Solana;
- attacks the Ethereum network and, after waiting for the confirmation of the transaction on the side of Solana, cancels it;
- the Solana-WETH contract ceases to be fully collateralized, as a result, the price of the wrapped assets of the rest of the users falls – in fact, they lose money.
“Even if there is a perfect bridge based ZK-SNARKwhich fully confirms the consensus, it is still vulnerable to theft through 51% attacks like this, ”he said.
According to Buterin, the interconnection of “hundreds” of blockchains through cross-chain bridges will lead to the emergence of many interdependent decentralized applications. In such a situation, a 51% attack even on one network creates a “systemic infection” that threatens the economy of the entire ecosystem.
“I don’t expect these problems to appear right away. Performing a 51% attack even on one chain is difficult and expensive. However, the more cross-chain bridges and applications are used, the more likely it becomes, ”he concluded.
The founder of the Frax Finance project, Sam Casemian, noted that there is a concept of a bridging that can solve the problem Buterin named. We are talking about a system that checks the states of blockchains interacting with the bridge before confirming a transaction, and then transmits this information to an anchor network, which can be Ethereum.
Jag Sidhu, CTO of Blockchain Foundry, drew attention to the fact that the zkLink cross-chain exchange is trying to implement a similar idea.
Zklink tries to do this sam, so the rollups are seperate then an outer proof is aggregated on each rollup to create a final proof that is put into each contracts and an oracle system pushes the proof to each chain to ensure it’s consistent. There are better ways but same idea
– jagdeep sidhu (@realSidhuJag) January 8, 2022
Recall that at the end of 2021, Buterin spoke about the role of ZK-Rollups in Ethereum scalability and proposed a method to reduce the cost of transactions in L2.
