In this case it's the bridge that's fairly centralized. There wasn't any hard forks or other manipulation of the underlying blockchains (except for sending transactions on them).
Exactly. Vitalik Buterin even shared his concerns on the fundamental security limits of cross-chain bridges earlier this year:
> For example, suppose that you have 100 ETH on Ethereum, and Ethereum gets 51% attacked, so some transactions get censored and/or reverted. No matter what happens, you still have your 100 ETH. Even a 51% attacker cannot propose a block that takes away your ETH, because such a block would violate the protocol rules and so it would get rejected by the network
> Now, imaging what happens if you move 100 ETH onto a bridge on Solana to get 100 Solana-WETH, and then Ethereum gets 51% attacked. The attacker deposited a bunch of their own ETH into Solana-WETH and then reverted that transaction on the Ethereum side as soon as the Solana side confirmed it. The Solana-WETH contract is now no longer fully backed, and perhaps your 100 Solana-WETH is now only worth 60 ETH. Even if there's a perfect ZK-SNARK-based bridge that fully validates consensus, it's still vulnerable to theft through 51% attacks like this.
tcgv|4 years ago
> For example, suppose that you have 100 ETH on Ethereum, and Ethereum gets 51% attacked, so some transactions get censored and/or reverted. No matter what happens, you still have your 100 ETH. Even a 51% attacker cannot propose a block that takes away your ETH, because such a block would violate the protocol rules and so it would get rejected by the network
> Now, imaging what happens if you move 100 ETH onto a bridge on Solana to get 100 Solana-WETH, and then Ethereum gets 51% attacked. The attacker deposited a bunch of their own ETH into Solana-WETH and then reverted that transaction on the Ethereum side as soon as the Solana side confirmed it. The Solana-WETH contract is now no longer fully backed, and perhaps your 100 Solana-WETH is now only worth 60 ETH. Even if there's a perfect ZK-SNARK-based bridge that fully validates consensus, it's still vulnerable to theft through 51% attacks like this.
[1] https://twitter.com/vitalikbuterin/status/147950136619213209...
jude-|4 years ago
ludamad|4 years ago