An external verification protocol is a protocol that uses a set of external validators to relay data between chains. This usually manifests itself as a secure multi-party computing (MPC) system, oracle network, or threshold signature (all of which are actually the same thing).

Advantage: • Allow completely universal messaging between domains; • Can be easily extended to any domain in the Ethereum ecosystem.

Disadvantages: • The user and/or LP fully trust the funds/data of the external validator. This means that the security of the model in terms of encryption economy is basically lower than the level of the underlying domain (similar to the comparison between Arbitrum and Optimism mentioned above).

In some cases, the project will use additional staking or bonding mechanisms to try to increase security for users. However, this is usually economically inefficient. In order to make the system trustless, users must cover the highest possible loss with mortgage assets, and these mortgage assets must be provided by the verifier. This not only significantly increases the capital required by the system, but firstly goes against the entire original intention of casting assets or liquidity pools.