Ethereum co-founder Vitalik Buterin doesn’t like cross-chain bridges.
How do cross-chain bridges work?
First- and second-generation blockchains are not able to communicate directly with each other, so bridges have been created that somehow allow information to be carried from one blockchain to another.
The most famous of these are those that allow tokens to be created on one blockchain that represent tokens or cryptocurrencies from other blockchains, such as WBTC on Ethereum.
But Buterin does not like this solution, because it presents fundamental limitations to the issue of security.
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
The security problems of cross-chain bridges (including on Ethereum)
According to Buterin, the future will not be cross-chain, but multi-chain, i.e. not with solutions that allow information to be carried from one blockchain to another, but with developments that will allow blockchains to talk to each other.
He cites as an example the problems associated with possible 51% attacks on blockchain combinations or bridges, and in particular the guarantees maintained even after such attacks.
For this reason, he always considers it safer to hold native assets on the same blockchain on which they were created, rather than holding them on another blockchain. As an example he cites the WETH tokens on Solana, which represent ETH on this blockchain, as Solana has probably been the subject of several attacks lately.
Buterin also says that he doesn’t expect this kind of problem to manifest itself in the short term, but that the greater the use of cross-chain bridges and apps, the worse the problem will become.
In the case of a 51% attack on a specific blockchain, hackers can censor, reverse or duplicate transactions, but not steal tokens. If, on the other hand, they attack a cross-chain bridge, they may be able to steal tokens locked in the smart contract used to duplicate tokens on another blockchain.
Furthermore, if we imagine a hypothetical cross-chain network with 100 different blockchains, the high level of interdependence and overlapping of derivatives could allow a hacker to attack a small blockchain, which is an easy target, and cause a systemic failure.
Multi-chain is better
The problem would therefore be cross-chain bridges, for which Buterin would in fact like to see more secure alternatives.
Today, unfortunately, the scenario is not yet multi-chain at all, so cross-chain solutions are the only ones really in use to allow different blockchains to talk to each other. But Ethereum itself is preparing to become increasingly multi-chain in the near future, with the aim of further raising the security level of these new technologies.