Interoperability

Interoperability in LinethLineth (Formerly the Linea Stack) The open-source ZK-rollup stack, codebase, and technical protocol that's the foundation of Linea Mainnet. Operators can deploy this stack to launch their own Ethereum-compatible L2 or L3 networks. is enabled by:

• Canonical token bridge: a protocol contract and process that allows token transfers with finalization guarantees.
• Message service: a generalized cross-chain messaging primitive for application data.

The Linea public network leverages the LineaRollup to support these functions. This smart contract provides the rollup and L1 message service for messages passed across the two domains, such as token transfers, contract calls, or state synchronization. Linea-to-Ethereum (L2 to L1) messages can be claimed on Ethereum only after the L2 batch is finalized: finalization verifies the batch's zk-SNARK proof and anchors the corresponding L2 message Merkle root on L1. The message is then accepted once a Merkle proof verifies its inclusion in that finalized root. Ethereum-to-Linea (L1 to L2) messages execute on Linea after the originating Ethereum transaction is verified against L1 state and finalized.

By anchoring messages to verified state roots, the contract facilitates cross-chain communication, ensuring Ethereum-level security and full transparency, while preserving the scalability benefits of Linea. The following sections cover in detail the protocol-level mechanisms that enable secure cross-chain communication, value transfer, and message verification between a Lineth network and other chains.