Protocol Research
Replay Resistance in Cross-Chain Messaging
A practical model for message uniqueness across domains, validator epochs and delayed execution.
A practical model for message uniqueness across domains, validator epochs and delayed execution.
The uniqueness boundary
A bridge message is only unique when its identity is bound to its origin domain, destination domain, nonce, payload and authorization context. Omitting any part of that tuple creates room for valid information to be interpreted twice.
Delayed delivery
Messages that outlive validator-set changes, pauses or upgrade windows deserve separate treatment. Their original authorization may remain cryptographically valid while no longer satisfying the current operational policy.
Design implication
Replay resistance should be enforced at several independent layers: source-state commitment, destination consumption state and application-level idempotency. Monitoring is evidence, not a substitute for rejection.
test assumptions at the boundary;
preserve evidence through failure;
make recovery an explicit system property.