Vitalik Buterin expressed his opposition to the use of cross-chain solutions byEthereum and otherBlockchains in favor of a multi-chain future, in a much-publicized tweet this past week.
Cross-chain bridges are not ideal for Buterin because they increase the security risks in the process of transferring assets. This tradeoff to security happens because of the increase in the attack vectors of the assets over a wider network surface area, as it is moved across an increasing number of chains and applications with different security principles.
If your ETH is contained withinEthereum, it depends only on the security validation of the network. The security of the ETH is now dependent on the security of the destination chain and any other cross-chain solutions that are used to transfer, wrap and lock up the asset when ETH is moved across different chains on cross-chain bridges.
Buterin puts it aptly in his tweet:
Imagine what would happen if 100 ETH were moved onto a bridge in Solana to get 100 Solana-WETH, and then Ethereum gets 51% attacked. The attacker deposited a lot of their own ETH into Solana-WETH and then reversed 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 maybe your 100 Solana-WETH is only worth 60 ETH. Even if there is a perfect ZK-SNARK-based bridge that fully validates consensus, it is still vulnerable to theft through 51% attacks like this. The spread of assets across different security networks makes chains more dependent on one another, since the same assets are being collateralized and used for different purposes. If a person were attacked, the increased risk could lead to a domino effect that would ripple through different blockchain ecosystems, as opposed to if the asset was in a single blockchain:
Buterin points out a key security problem of cross-chain bridges, but its risks do not stop there. Today, the majority of cross-chain bridges facilitate asset transfers through centralized federations and external validators.
Transactions are cheaper and quicker because of these solutions, which bypasses the arduous process of chain validation. Popular examples include BitGo s Wrapped Bitcoin WBTC Axie Infinity's Ronin Bridge, Terra s Shuttle Bridge and much more.
This also means that transactions are moving away from a trustless form of verification, resulting in an increased reliance on the operator of the cross-chain bridge rather than the decentralized security of the underlying network.
The key risks of cross-chain solutions can be summarized as being grounded in two points. Cross-chain solutions increase the number of attack vectors for the assets, intensifying the spread of contagion risk across chains. The transferred assets are then funneled through a variety of external validator networks that may no longer remain decentralized and trustless, increasing the risk across those same attack vectors.
Cross-chain bridges are popular among users for the simple reason that it offers a premium in speed and low costs. It is a temporary bandaid on a larger problem. They must come off as with all bandaids.
Like Buterin, Kadan Stadelmann, CTO of Komodo, believes that this security risk will gradually become heightened in awareness and accelerate the path towards the multi-chain future:
Multi-chain ecosystems, sometimes referred to as Layer 0 chains, such as Cosmos and Polkadot, are designed to avoid the security problems of cross-chain bridges. The PolkadotBlockchain allows Dapp developers to set up their own customizedchains on top of its foundation. The Polkadot main Relay Chain hub is used to coordinate security and the transfer of assets across all its chains.
The concept is similar to Cosmos, which consists of an ecosystem of multiple independent Cosmos chains called zones that can send token and data to one another. There are multiple central hubs that zones can plug into to reach other zones, unlike Polkadot. The Cronos chain of cryptocurrencies, THORChain and Terra are some of the most popular names that have settled on Cosmos.
Polkadot and Cosmos want to ensure interoperability of assets while guaranteeing the trustless transfer of assets that do not require users to place their trust in intermediary entities like cross-chain solutions.