Cross-Chain Token Standard - Tokens (EVM)

Before enabling an ERC20-compatible token in CCIP, it's important to understand the requirements it must fulfill to integrate with CCIP.

Registration functions

A token administrator can use any of the following supported function signatures for enabling their tokens in CCIP:

• owner(): This function returns the token contract owner's address.
• getCCIPAdmin(): This function returns the token administrator's address and is recommended for new tokens, as it allows for abstraction of the CCIP Token Administrator role from other common roles, like owner().

Transfer functions

The token's smart contract must meet minimum requirements to integrate with CCIP.

BurnMint Requirements

This section describes the requirements for tokens that are used with the BurnMint token pools.

• The token smart contract must have the following functions:

  • mint(address account, uint256 amount): This function is used to mint the amount of tokens to a given account on the destination blockchain.
  • burn(uint256 amount): This function is used to burn the amount of tokens on the source blockchain.
  • decimals(): Returns the token's number of decimals.
  • balanceOf(address account): Returns the current token balance of the specified account.
  • burnFrom(address account, uint256 amount): This function burns a specified number of tokens from the provided account on the source blockchain. Note: This is an optional function. We generally recommend using the burn function, but if you use a tokenPool that calls burnFrom, your token contract will need to implement this function.

• The token contract must support granting mint and burn permissions. The token developers or another role (such as the token administrator) will grant these permissions to the token pool.

LockRelease Requirements

This section describes the requirements for tokens that are used with the LockRelease token pools.

• The token smart contract must have the following functions:

  • decimals(): Returns the token's number of decimals.
  • balanceOf(address account): Returns the current token balance of the specified account.

• On the destination blockchain, the token contract must support granting mint and burn permissions. The token developers or another role (such as the token administrator) will grant these permissions to the token pool.

Token Handling Mechanisms

To facilitate cross-chain token transfers, you need to choose the appropriate token handling mechanism and deploy the correct combination of token pools for the source and destination blockchains. The table below summarizes the different token handling mechanisms and the recommended token pools to deploy for each scenario, ensuring a seamless token transfer process.