MessageTransmitter

Cross-Chain Transfer Protocol (CCTP) is a permissionless on-chain utility that can burn native USDC on a source chain and mint native USDC of the same amount on a destination chain. This is made possible by two primary CCTP contracts found on each chain, MessageTransmitter and TokenMessenger.

receiveMessage

Messages with a given nonce can only be broadcast successfully once for a pair of domains. The message body of a valid message is passed to the specified recipient for further processing.

Parameters

Field	Type	Description
message	bytes calldata	Message bytes.
attestation	bytes calldata	signed attestation of message.

sendMessage

Sends a message to the destination domain and recipient. Emits a MessageSent event which will be attested by Circle’s attestation service.

Parameters

Field	Type	Description
destinationDomain	uint32	Destination domain identifier.
recipient	bytes32	Address to handle message body on destination domain.
messageBody	bytes calldata	Application-specific message to be handled by recipient.

sendMessageWithCaller

Same as sendMessage, but with an additional parameter, destinationCaller. This parameter specifies which address has permission to call receiveMessage on the destination domain for this message.

Parameters

Field	Type	Description
destinationDomain	uint32	Destination domain identifier.
recipient	bytes32	Address of message recipient on destination domain as bytes32.
destinationCaller	bytes32	Caller on the destination domain, as bytes32.
messageBody	bytes calldata	Application-specific message to be handled by recipient.

replaceMessage

Replace a message with a new message body and/or destination caller. The originalAttestation must be a valid attestation of originalMessage, produced by Circle’s attestation service.

Parameters

Field	Type	Description
originalMessage	bytes calldata	Original message to replace.
originalAttestation	bytes calldata	Attestation of originalMessage.
newMessageBody	bytes calldata	New message body of replaced message.
newDestinationCaller	bytes32	The new destination caller, which may be the same as the original destination caller, a new destination caller, or an empty destination caller (bytes32(0), indicating that any destination caller is valid.)