Blockchain & Cryptocurrency Glossary

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

  • search-icon Clear Definitions
  • search-icon Practical
  • search-icon Technical
  • search-icon Related Terms

Cross-Domain Messaging

1 min read
Pronunciation
[kraws-doh-mayn mes-ij-ing]
Analogy
Like a courier service that picks up a package at one location and delivers it with proof of receipt at another.
Definition
A protocol for sending messages between execution environments or layers (e.g. Layer‑1 to Layer‑2), ensuring ordered, guaranteed delivery and proof of inclusion.
Key Points Intro
Cross‑domain messaging links separate execution contexts with reliable message delivery.
Key Points

Inbox/outbox: Each domain has queues for sent and received messages.

Proof verification: Merkle or SNARK proofs validate inclusion.

Sequencing: Ensures relative order of messages.

Retries/fallbacks: Handles temporary failures or reorgs.

Example
Optimism’s L1>L2 bridge uses `L1CrossDomainMessenger` and `L2CrossDomainMessenger` contracts to relay function calls with proofs of L1 inclusion.
Technical Deep Dive
Messages hashed into L1 state roots, included in L2 via state commitment chains. L2 contract verifies L1 proof via Merkle Patricia proof checking. Nonces prevent replay; gas limits avoid DoS.
Security Warning
Incorrect proof verification can allow unauthorized calls; use battle‑tested messenger contracts.
Caveat
Message latency depends on challenge periods and finality times of each domain.
Related Terms
Nonce

Cross-Domain Messaging - Related Articles

No related articles for this term.