EVM Smart Contracts

CCTP Smart Contracts for EVM-compatible blockchains

Contract Responsibilities

  • TokenMessenger: Entrypoint for cross-chain USDC transfer. Routes messages to burn USDC on a source chain, and mint USDC on a destination chain.
  • MessageTransmitter: Generic message passing. Sends all messages on the source chain, and receives all messages on the destination chain.
  • TokenMinter: Responsible for minting and burning USDC. Contains chain-specific settings used by burners and minters.

*Full contract source code is available at https://github.com/circlefin/evm-cctp-contracts.

Mainnet Contract Addresses

TokenMessenger: Mainnet

MessageTransmitter: Mainnet

TokenMinter: Mainnet

Testnet Contract Addresses

TokenMessenger: Testnet

MessageTransmitter: Testnet

TokenMinter: Testnet

Interface

The interface below serves as a reference for permissionless messaging functions exposed by the TokenMessenger and MessageTransmitter functions. The full ABIs are listed here.

TokenMessenger

depositForBurn

Deposits and burns tokens from sender to be minted on destination domain. Minted tokens will be transferred to mintRecipient.

Parameters

FieldTypeDescription
amountuint256Amount of tokens to deposit and burn.
destinationDomainuint32Destination domain identifier.
mintRecipientbytes32Address of mint recipient on destination domain.
burnTokenaddressAddress of contract to burn deposited tokens on local domain.

depositForBurnWithCaller

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

Parameters

FieldTypeDescription
amountuint256Amount of tokens to deposit and burn.
destinationDomainuint32Destination domain identifier.
mintRecipientbytes32Address of mint recipient on destination domain.
burnTokenaddressAddress of contract to burn deposited tokens on local domain.
destinationCallerbytes32Address of caller on the destination domain.

replaceDepositForBurn

Replace a BurnMessage to change the mint recipient and/or destination caller. Allows the sender of a previous BurnMessage (created by depositForBurn or depositForBurnWithCaller) to send a new BurnMessage to replace the original. The new BurnMessage will reuse the amount and burn token of the original, without requiring a new deposit.

This is useful in situations where the user specified an incorrect address and has no way to safely mint the previously burned USDC.

📘

The sender of the original depositForBurn has access to call replaceDepositForBurn. The resulting mint will supersede the original mint, as long as the original mint has not confirmed yet on-chain. When using a third-party app/bridge that integrates with CCTP to burn and mint USDC, it is the choice of the app/bridge if and when to replace messages on behalf of users. When sending USDC to smart contracts, be aware of the functionality that those contracts have and their respective trust model.

Parameters

FieldTypeDescription
originalMessagebytes calldataOriginal message bytes (to replace).
originalAttestationbytes calldataOriginal attestation bytes.
newDestinationCallerbytes32The new destination caller, which may be the same as the original destination caller, a new destination caller, or an empty destination caller, indicating that any destination caller is valid.
newMintRecipientbytes32The new mint recipient, which may be the same as the original mint recipient, or different.

MessageTransmitter

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

FieldTypeDescription
messagebytes calldataMessage bytes.
attestationbytes calldataSigned 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

FieldTypeDescription
destinationDomainuint32Destination domain identifier.
recipientbytes32Address to handle message body on destination domain.
messageBodybytes calldataApplication-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 the message.

Parameters

FieldTypeDescription
destinationDomainuint32Destination domain identifier.
recipientbytes32Address of message recipient on destination domain.
destinationCallerbytes32Address of caller on the destination domain.
messageBodybytes calldataApplication-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

FieldTypeDescription
originalMessagebytes calldataOriginal message to replace.
originalAttestationbytes calldataAttestation of originalMessage.
newMessageBodybytes calldataNew message body of replaced message.
newDestinationCallerbytes32The 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).