‣
- In order for a bridge between two rollup chains to be trust-minimized, the rollup chains must verify the fraud or ZK proofs of each other, which means they must understand the state machine of each other (proof-based bridges).
‣
- However, committee-based bridges also exist (such as IBC bridges today), where instead of relying on proofs for state validity, the bridge relies on a committee to attest to the validity of blocks. Such a bridge is not trust-minimized, as the committee can steal funds. However, such bridges may have lower complexity as the destination chain does not need to have functionality to process fraud or ZK proofs of the source chain.
- In current IBC bridges, the committee is the validator set of the source chain. However, one can envision a world where the committee is operated by specialized bridge providers that attest to multiple chains. This can be thought of as interchain security for bridges only, rather than block production. In such a setup, the bridge committee is decoupled from the validator set of the source chain.