ERC-5164: Cross-Chain Execution

ERC-5164 defines an interface that supports execution across EVM networks. This repo contains the IMessageDispatcher and IMessageExecutor interfaces for use with ERC-5164 compliant messengers. This repo also provides two convenience contracts that can be extended, MessageExecutor and MessageReceiver.

Implementing ERC-5164

Dispatch a message

Your MessageDispatcher should inherit from IMessageDispatcher and implement the dispatchMessage function. When dispatchMessage is called, it's recommended to encode the message and transport it to its destination. Transporting a message may involve emiting a special event, storing a hash of the message, or passing it to external transport layer like a rollup's native message bridge.

Example:

contract MyMessageDispatcher is IMessageDispatcher {
    function dispatchMessage(uint256 toChainId, address to, bytes calldata data) external payable returns (bytes32) {
        bytes32 messageId = keccak256(abi.encode(
            block.chainid,
            msg.sender,
            toChainId,
            to,
            data
        ));

        emit MessageSent(messageId, msg.sender, toChainId, to, data);

        transportLayer.transport(toChainId, messageId);

        return messageId;
    }
}

Execute a message

Your MessageExecutor should inherit from IMessageExecutor. Each implementation may choose how the message execution is initiated. When a messsage is executed, the ERC-5164 validation data (messageId, fromChainId, from) should be appended to the message's data payload. The provided MessageExecutor convenience contract does this automatically when you call execute.

Example:

contract MyMessageExecutor is MessageExecutor {
    function executeMessage(
        uint256 fromChainId,
        address from,
        address to,
        bytes calldata data,
        Proof memory proof
    ) external {
        require(proof.isValid, "Invalid proof");

        bytes32 messageId = keccak256(abi.encode(
            fromChainId,
            msg.sender,
            block.chainid,
            to,
            data
        ));

        _execute(messageId, fromChainId, from, to, data);
    }
}

Receive a message

When receiving a message, inherit from MessageReceiver to access the EIP-5164 validation data -- messageId, from, and fromChainId.

Example:

contract MyContract is MessageReceiver {
    event MyMessageHandleEvent {
        bytes32 indexed messageId /*,
        ... your event params*/
    }

    function myFunction() external {
        // Parse the cross-chain context from the call
        (bytes32 messageId, address from, uint256 fromChainId) = _crossChainContext();

        // Validate the cross-chain caller
        require(msg.sender == hopMessageBridge, "Invalid sender");
        require(from == expectedCrossChainSender, "Invalid cross-chain sender");
        require(fromChainId == expectedCrossChainId, "Invalid cross-chain chainId");

        // Execute your business logic
        emit MyMessageHandleEvent(messageId, /* your event params */);
    }
}

Usage

Compile Contracts

npm run compile