The next generation of bridges aims to be trust-minimized and highly secure, enabling a seamless exchange of value between different blockchains. The question of complete safety when bridging across blockchains remains, leading to consideration of staying within a single blockchain ecosystem or exploring Layer 2 rollups as potentially better alternatives.
Daniel Lumi, an Independent Researcher and Consultant specializing in zero-knowledge, L2 technology, DAOs, and privacy, delivered a talk on the state of bridges in Web3 at EthCC.
He emphasized that many hacks in the blockchain space have been associated with bridge vulnerabilities, resulting in substantial capital losses exceeding $2 billion from the X Infinity Bridge, The Nomad Bridge, and the Solana Wormhole Bridge hacks.
Lumi expressed the need for improved bridges in a world with multiple chains, stating, “We live in a world with many chains, and if we do live in that world, we definitely need better bridges than we currently have.”
Blockchain bridges serve as mechanisms that enable interoperability between different blockchains, facilitating seamless transfers of assets, data, or messages.
They play a critical role in enhancing cross-chain transactions, data sharing, and communication within the blockchain ecosystem. By connecting blockchains, bridges enhance overall functionality, scalability, and liquidity.
Challenges with bridges
The speaker cited specific problems associated with bridges, which include bridge upgrades, smart contract bugs, and verifier issues in ZK proofs.
He pointed out that the reality is that while bridges such as multi-sig, custodial bridges, and optimistic fraud-proof-based bridges are most commonly used today, there is still room for improvement in how they are designed.
He added that the focus when designing the next generation of cross-chain bridges should be on “light client” bridges, which are native to the protocol, and “ZK bridges,” which use zero-knowledge proofs.
A light client in a blockchain context refers to a method of accessing and verifying data on a blockchain without needing to download the entire blockchain history.
Instead of re-executing every transaction, a light client only downloads the latest state of the blockchain, allowing users to see their balances and perform transactions without the need for extensive data processing.
In the context of bridges, light clients can be utilized to achieve trust-minimized cross-chain communication.
Instead of fully integrating one blockchain into another to create a trustless bridge, light clients enable the submission of the latest state of one blockchain to a bridge contract on another blockchain.
This approach reduces the need for absolute trust in intermediaries and provides benefits such as user-enforced transactions and improved latency.
L2+ Bridges
Highlighting the benefits and issues with each kind of bridge design, he said that to improve Layer 2 bridges, there is a need to look into the security and trust architecture.
He also added that Layer 1 chains are still important as well for trustless message passing which can help mitigate risks associated with cross-chain bridges.
The researcher also revealed the concept of L2+ bridges, where multiple Layer 2 chains use the same bridge, and how this approach can improve scalability and user experience.
In addition, Daniel said that other solutions to apply when solving the bridge problem are to improve bridge security, such as implementing circuit breakers, delay periods for upgrades, and multiple verifiers to enhance fault tolerance.
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