Verification Mechanisms

Nomad's primary design difference from other cross-chain messaging protocols is its usage of optimistic verification.

By leveraging an optimistic mechanism, Nomad reduces the trust assumptions relative to externally verified systems (eg. multisig, PoS, and oracle based designs). While these systems require an honest majority (k-of-n) to function safely, Nomad only requires a single honest watcher (1-of-n).

This section will provide:

• A background on verification in the context of cross-chain communications

• A description of the different verification mechanisms:

  • Native verification — why it is the ideal, but impractical

  • External verification — why it has proliferated, but is insecure

  • Optimistic verification — how it reaches a via media, and what it trades off

• A comparison of the different mechanisms and popular constructions