Programmatically Create a Canonical Interchain Token Using the Interchain Token Service

If you have an ERC-20 token on one or more blockchains and you want to make the token interoperable across chains, the Interchain Token Service provides a solution. You can transform an ERC-20 token into an Interchain Token by deploying a token manager.

If you would like to create a wrapped, bridgeable version of your ERC-20 token on other chains, you can register it as a Canonical Interchain Token using the InterchainTokenFactory contract.

Each token can only be registered once as a Canonical Interchain Token. This ensures unique and streamlined token management across different blockchains. Though you can register your Canonical Interchain Token directly through the Interchain Token Portal, there are times where you may want to do so programmatically, such as when you have already deployed a token on one chain and wish to deploy a wrapped version of that token on another chain.

In this tutorial, you will learn how to:

• Programmatically create a Canonical Interchain Token from scratch using Axelar’s Interchain Token Service
• Register a Canonical Interchain Token on the Fantom chain
• Deploy remote Canonical Interchain Token on the Polygon chain
• Transfer your token between Fantom and Polygon

Prerequisites

You will need:

• A basic understanding of Solidity and JavaScript
• A wallet with FTM and MATIC funds for testing. If you don’t have these funds, you can get FTM from the Fantom faucet and MATIC from the Mumbai faucets (1, 2).

Deploy an ERC-20 token on the Fantom testnet

Create a SimpleERC20 token and give it a name and symbol. You can skip this step if you already have an ERC-20 token deployed on the Fantom testnet.

Set up your development environment

Create and initialize a project

Open up your terminal and navigate to any directory of your choice. Run the following commands to create and initiate a project:

mkdir canonical-interchain-token-project && cd canonical-interchain-token-project
npm init -y

Install Hardhat and the AxelarJS SDK

Install Hardhat and the AxelarJS SDK with the following commands:

npm install --save-dev hardhat@2.18.1 dotenv@16.3.1
npm install @axelar-network/axelarjs-sdk@0.13.9 crypto@1.0.1 @nomicfoundation/hardhat-toolbox@2.0.2

Set up project ABIs

Next, set up the ABIs for the Interchain Token Service, Interchain Token Factory, and the contract from the token you deployed.

Create a folder named utils. Inside the folder, create the following new files and add the respective ABIs:

• Add the Interchain Token Service ABI to interchainTokenServiceABI.json.
• Add the Interchain Token Factory ABI to interchainTokenFactoryABI.json.
• Add your custom token ABI to customTokenABI.json. You can get this from FTMScan with the address of your deployed token.

Set up an RPC for the local chain

Back in the root directory, set up an RPC for the Fantom testnet. You will use this as your local (source) chain.

Create an .env file

To make sure you’re not accidentally publishing your private key, create an .env file to store it in:

touch .env

Add your private key to .env and hardhat.config.js

Export your private key and add it to the  .env file you just created:

PRIVATE_KEY= // Add your account private key here

Then, create a file with the name hardhat.config.js and add the following code snippet:

require("@nomicfoundation/hardhat-toolbox");
require("dotenv").config({ path: ".env" });

const PRIVATE_KEY = process.env.PRIVATE_KEY;

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
  solidity: "0.8.18",
  networks: {
    fantom: {
      url: "https://rpc.ankr.com/fantom_testnet",
      chainId: 4002,
      accounts: [PRIVATE_KEY],
    },
  },
};

Register a Canonical Interchain Token on a local chain

Now that you have set up an RPC for the Fantom testnet, you can register a Canonical Interchain Token.

Create a canonicalInterchainToken.js script

Create a new file named canonicalInterchainToken.js and import the required dependencies:

• Ethers.js
• The AxelarJS SDK
• The custom token contract ABI
• The address of the InterchainTokenService contract
• The address of the InterchainTokenFactory contract

const hre = require("hardhat");
const crypto = require("crypto");
const {
  AxelarQueryAPI,
  Environment,
  EvmChain,
  GasToken,
} = require("@axelar-network/axelarjs-sdk");

const interchainTokenServiceContractABI = require("./utils/interchainTokenServiceABI");
const interchainTokenFactoryContractABI = require("./utils/interchainTokenFactoryABI");
const customTokenContractABI = require("./utils/customTokenABI");

const MINT_BURN = 0;
const LOCK_UNLOCK = 2;

// Addresses on mainnet/testnet
const interchainTokenServiceContractAddress =
  "0xB5FB4BE02232B1bBA4dC8f81dc24C26980dE9e3C";
const interchainTokenFactoryContractAddress =
  "0x83a93500d23Fbc3e82B410aD07A6a9F7A0670D66";
const customTokenAddress = "0x0EF6280417A1BF22c8fF05b54D7A7928a173E605"; // your token address

Get the signer

Next, create a getSigner() function in canonicalInterchainToken.js. This will obtain a signer for a secure transaction:

//...

async function getSigner() {
  const [signer] = await ethers.getSigners();
  return signer;
}

Get the contract instance

Then, create a getContractInstance() function in canonicalInterchainToken.js . This will get the contract instance based on the contract’s address, ABI, and signer:

//...

async function getContractInstance(contractAddress, contractABI, signer) {
  return new ethers.Contract(contractAddress, contractABI, signer);
}

Register Canonical Interchain Token

Now you’re ready to register your token as a Canonical Interchain Token! Create a registerCanonicalInterchainToken() function for the Fantom testnet. This will register a Canonical Interchain Token with your custom token address:

// Register Canonical Interchain Token to the Fantom chain.
async function registerCanonicalInterchainToken() {
  // Get a signer to sign the transaction
  const signer = await getSigner();

  // Create contract instances
  const interchainTokenFactoryContract = await getContractInstance(
    interchainTokenFactoryContractAddress,
    interchainTokenFactoryContractABI,
    signer
  );
  const interchainTokenServiceContract = await getContractInstance(
    interchainTokenServiceContractAddress,
    interchainTokenServiceContractABI,
    signer
  );

  // Register a new Canonical Interchain Token
  const deployTxData =
    await interchainTokenFactoryContract.registerCanonicalInterchainToken(
      customTokenAddress // Your token address
    );

  // Retrieve the token ID of the newly registered token
  const tokenId =
    await interchainTokenFactoryContract.canonicalInterchainTokenId(
      customTokenAddress
    );

  const expectedTokenManagerAddress =
    await interchainTokenServiceContract.tokenManagerAddress(tokenId);

  console.log(
    `
  Transaction Hash: ${deployTxData.hash},
  Token ID: ${tokenId},
  Expected Token Manager Address: ${expectedTokenManagerAddress},
     `
  );
}

Add a main() function

Add a main() function to execute the canonicalInterchainToken.js script. It will handle any errors that may arise:

//...

async function main() {
  const functionName = process.env.FUNCTION_NAME;
  switch (functionName) {
    case "registerCanonicalInterchainToken":
      await registerCanonicalInterchainToken();
      break;
    default:
      console.error(`Unknown function: ${functionName}`);
      process.exitCode = 1;
      return;
  }
}

main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

Run the canonicalInterchainToken.js script to deploy to Fantom

Run the script in your terminal to register and deploy the token, specifying the fantom testnet:

FUNCTION_NAME=registerCanonicalInterchainToken npx hardhat run canonicalInterchainToken.js --network fantom

If you see something similar to the following on your console, you have successfully registered your token as a Canonical Interchain Token.

Transaction Hash: 0x551cdba803a55bc8989a8eb74165c03563590f8f0161b0eb1308ae3953295de8,
Token ID: 0x1fe2d9bf8d6d7288224e83399696bcc7ac60421723e6150f8de800e8b1015a7a,
Expected Token Manager Address: 0x1d680d2B53aEf3E0aDdC7544105A9ae6091bA793,

Store the token ID

Copy the token ID and store it somewhere safe. You will need it to initiate a remote token transfer in a later step.

Check the transaction on the Fantom testnet scanner

Check the Fantom testnet scanner to see if you have successfully registered your token as a Canonical Interchain Token.

Deploy Remote Canonical Interchain Token

You’ve just successfully a Canonical Interchain Token to Fantom, which you are using as your local chain. Now, deploy the token remotely to Polygon, which will be the remote chain in this tutorial. Remember that you can specify any two chains to be your local and remote chains.

Estimate gas fees

In canonicalInterchainToken.js, call estimateGasFee() from the AxelarJS SDK to estimate the actual cost of deploying your remote Canonical Interchain Token on a remote chain:

//...

const api = new AxelarQueryAPI({ environment: Environment.TESTNET });

// Estimate gas costs.
async function gasEstimator() {
  const gas = await api.estimateGasFee(
    EvmChain.FANTOM,
    EvmChain.POLYGON,
    GasToken.FTM,
    700000,
    1.1
  );

  return gas;
}

//...

Perform remote token deployment

Create a deployRemoteCanonicalInterchainToken() function that will perform token remote canonical deployment on the Polygon Mumbai testnet.

//...

// deployRemoteCanonicalInterchainToken: On Polygon
async function deployRemoteCanonicalInterchainToken() {
  // Get a signer for authorizing transactions
  const signer = await getSigner();

  // Get contract for remote deployment
  const interchainTokenFactoryContract = await getContractInstance(
    interchainTokenFactoryContractAddress,
    interchainTokenFactoryContractABI,
    signer
  );

  // Estimate gas fees
  const gasAmount = await gasEstimator();

  // Initiate transaction
  const txn =
    await interchainTokenFactoryContract.deployRemoteCanonicalInterchainToken(
      "Fantom",
      customTokenAddress, // Your token address
      "Polygon",
      gasAmount,
      { value: gasAmount }
    );

  console.log(`Transaction Hash: ${txn.hash}`);
}

//...

Update main() to deploy to remote chains

Update main() to execute deployRemoteCanonicalInterchainToken() :

//...

async function main() {
  const functionName = process.env.FUNCTION_NAME;
  switch (functionName) {
    //...
    case "deployRemoteCanonicalInterchainToken":
      await deployRemoteCanonicalInterchainToken();
      break;
    default:
    //...
  }
}

//...

Run the canonicalInterchainToken.js script to deploy to Polygon

Run the script in your terminal to to deploy remote Canonical Interchain Token, once again specifying the fantom testnet (the source chain where all transactions are taking place):

FUNCTION_NAME=deployRemoteCanonicalInterchainToken npx hardhat run canonicalInterchainToken.js --network fantom

You should see something similar to the following on your console:

Transaction Hash: 0xb963f5ce3402e1787ead0c8f421be79ac06e5b78305b1dbce184806e099d54fd

Check the transaction on the Axelar testnet scanner

Check the Axelarscan testnet scanner to see if you have successfully deployed the remote Canonical Interchain Token “MAT” on the Polygon Mumbai testnet. It should look something like this. Make sure that Axelar shows a successful transaction before continuing on to the next step.

Transfer your token between chains

Now that you have registered and deployed a Canonical Interchain Token both locally to Fantom and remotely to Polygon, you can transfer between those two chains via the interchainTransfer() method.

Initiate a remote token transfer

In canonicalInterchainToken.js, create a transferTokens() function that will facilitate remote token transfers between chains. Change the token ID to the tokenId that you saved from an earlier step, and change the address in transfer to your own wallet address:

//...

// Transfer token between chains.
async function transferTokens() {
  const signer = await getSigner();

  const interchainTokenServiceContract = await getContractInstance(
    interchainTokenServiceContractAddress,
    interchainTokenServiceContractABI,
    signer
  );

  const customTokenContract = await getContractInstance(
    customTokenAddress,
    customTokenContractABI,
    signer
  ); // Approve ITS to spend tokens

  await customTokenContract.approve(
    interchainTokenServiceContractAddress,
    ethers.utils.parseEther("50")
  );

  const gasAmount = await gasEstimator();

  // Send via token
  const transfer = await interchainTokenServiceContract.interchainTransfer(
    "0x1fe2d9bf8d6d7288224e83399696bcc7ac60421723e6150f8de800e8b1015a7a", // token ID from  registerCanonicalInterchainToken
    "Polygon", // Destination chain
    "0x510e5EA32386B7C48C4DEEAC80e86859b5e2416C", // Destination address. Update with your own wallet address
    ethers.utils.parseEther("50"), // Amount to transfer
    "0x00",
    gasAmount, // gasValue
    { value: gasAmount }
  );

  console.log("Transfer Transaction Hash:", transfer.hash);
}

Update main() to execute token transfer

Update the main() to execute transferTokens():

//...

async function main() {
  const functionName = process.env.FUNCTION_NAME;
  switch (functionName) {
    //...
    case "transferTokens":
      await transferTokens();
      break;
    default:
    //...
  }
}

//...

Run the canonicalInterchainToken.js script to transfer tokens

Run the script in your terminal, specifying the fantom testnet:

FUNCTION_NAME=transferTokens npx hardhat run canonicalInterchainToken.js --network fantom

You should see something similar to the following on your console:

Transfer Transaction Hash: 0x3f3632918d68e2129c08a354b619be29906423062e1c700c7bb32118231a20e9

If you see this, it means that your interchain transfer has been successful! 🎉

reason: 'nonce has already been used',
code: 'NONCE_EXPIRED',
error: ProviderError: nonce too low

Check the transaction on the Axelar testnet scanner

Check the Axelarscan testnet scanner to see if you have successfully transferred MAT from the Fantom testnet to the Polygon testnet. It should look something like this.

Import the new token into your wallet

You can also import the new token into your own wallet with its contract address that you saved from FTMScan.

Congratulations!

You have now programmatically created a Canonical Interchain Token using Axelar’s Interchain Token Service and transferred it between two chains. You should now be able to confidently create and manage your own Interchain Tokens, opening up a wide range of possibilities for token transfers and asset bridges.

Great job making it this far! To show your support to the author of this tutorial, please post about your experience and tag @axelarnetwork on Twitter (X).

What’s next

For further examples utilizing the Interchain Token Service, check out the following in the axelar-examples repo on GitHub:

• its-custom-token — Demonstrates how to use the ITS with a custom token implementation.
• its-interchain-token — Demonstrates how to deploy Interchain Tokens that are connected across EVM chains and how to send some tokens across.
• its-canonical-token - Demonstrates how to deploy canonical Interchain Token and send cross-chain transfer for these tokens.
• its-lock-unlock-fee Demonstrates how to deploy deploy interchain token with lock/unlock_fee token manager type.
• its-executable Demonstrates how to deploy interchain token and send a cross-chain transfer along with a message.
• its-mint-burn-from Demonstrates how to deploy interchain token with uses burnFrom() on token being bridged rather than burn().

References

• Interchain Token Service Documentation
• Interchain Tokens GitHub Repository
• AxelarJS SDK