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Cover image for [Informative] Step-by-Step Guide: USDC Stablecoin Integration on XDC Blockchain
AnilChinchawale
AnilChinchawale

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[Informative] Step-by-Step Guide: USDC Stablecoin Integration on XDC Blockchain

#xdc #usdc #stablecoin #blockchain

In the world of cryptocurrencies, stablecoins play a crucial role in providing stability and reliability to transactions. The USDC (USD Coin) stablecoin is one such prominent example, known for its backing by US dollars on a 1:1 basis. This article outlines the process of deploying the USDC stablecoin on the XDC blockchain, detailing the steps followed and the resulting output.

Check out the “Deployment.md” file to know the deployment structure in a better way.

Installation (Prerequisites):

1. NVM Installation:

Begin by installing nvm (Node Version Manager), a tool for managing multiple Node.js versions.
Execute the following command in your terminal:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash
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2. Node and Yarn Installation:

This project requires specific versions of Node.js and Yarn.
Install Node.js version 16.14.0 and Yarn version 1.22.19 using nvm:

nvm install 16.14.0
nvm use 16.14.0
npm install -g yarn@1.22.19
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3. Stablecoin-EVM Installation:

Clone the stablecoin-EVM repository and switch to the appropriate branch.

git clone https://github.com/XinFinOrg/stablecoin-evm
cd stablecoin-evm
git checkout xdcnetwork
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After configuring the environment and setting up the prerequisites, the deployment process involves several key steps to ensure the stability and functionality of the stablecoin-EVM project. Below are the detailed deployment commands along with their functionalities:

yarn
yarn compile
yarn hardhat typechain
yarn test
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4. Configurations:

Create and configure the .env file with the necessary parameters.

echo "[]" > blacklist.remote.json
cp .env.example .env
vi .env
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Sample .env Configuration:

DEPLOYER_PRIVATE_KEY="0x......"
TOKEN_NAME=USDC
TOKEN_SYMBOL=USDC
TOKEN_CURRENCY=USD
TOKEN_DECIMALS=6
PROXY_ADMIN_ADDRESS="0x......"
OWNER_ADDRESS="0x......"
MASTER_MINTER_OWNER_ADDRESS="0x......"
GAS_MULTIPLIER=110
BLACKLIST_FILE_NAME=blacklist.remote.json
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Note:

  • Ensure PROXY_ADMIN_ADDRESS differs from OWNER_ADDRESS.
  • PAUSER_ADDRESS is optional, will be OWNER_ADDRESS if not set
  • BLACKLISTER_ADDRESS is optional, will be OWNER_ADDRESS if not set
  • LOST_AND_FOUND_ADDRESS is optional, will be OWNER_ADDRESS if not set

5. Deployment on Testnet(XDC Apothem): 

# forge script -vv --broadcast --legacy scripts/deploy/deploy-fiat-token.s.sol --rpc-url https://earpc.apothem.network/
yarn deploy:xdc:test
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Output:

== Return ==
0: contract FiatTokenV2_2 0xC6386Aa0b5d25b7827ed23C7e66865A0CB87c90e
1: contract MasterMinter 0x8983d06244F6E503a4640e36C4d86dB532729F90
2: contract FiatTokenProxy 0xf16f48Ba54282Be2C9D267a56fDA6Caad3329600
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Interaction with FiatToken contract

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Roles: The FiatToken has a number of roles (addresses) which control different functionality:

masterMinter (0x8983d06244F6E503a4640e36C4d86dB532729F90)

  • adds and removes minters and increases their minting allowance minters - create and destroy tokens.

pauser (0x774fc390A602706811F49d826Ec10Bbf1135c8a0)

  • pause the contract, which prevents all transfers, minting, and burning.

blacklister (0x2230091cD557A3211296d7A2E8d85E22064945C8)

  • prevent all transfers to or from a particular address, and prevents that address from minting or burning.

owner (0x774fc390A602706811F49d826Ec10Bbf1135c8a0)

  • re-assign any of the roles except for admin.

admin (0x486a98b0f5d84d265e2403dfbb6ad1abe52ecb91)

  • manage the proxy-level functionalities such as switching the implementation contract.

rescuer (0x2230091cD557A3211296d7A2E8d85E22064945C8)

  • transfer any ERC-20 tokens that are locked up in the contract Circle will control the address of all roles.

FiatToken Contract Interaction

Owner

The owner of the FiatToken contract can set the masterMinter role to point to the address of the MasterMinter contract. This enables the MasterMinter contract to call minter management functions on the FiatToken contract:

  • configureMinter(minter, allowance) - Enables the minter and sets its minting allowance.
  • removeMinter(minter) - Disables the minter and sets its minting allowance to 0.
  • isMinter(minter) - Returns true if the minter is enabled, and false otherwise.

  • minterAllowance(minter) - Returns the minting allowance of the minter.

  • Owner adds and removes controllers, sets the address of the minterManager, and sets the owner. Re-assign any of the roles except for admin

  • transferOwnership updates the owner role to a new address.

  • transferOwnership may only be called by the owner role.

  • transferOwnership(address newOwner) Interaction with FiatTokenProxy contract

Admin

  • Manage the proxy-level functionalities such as switching the implementation contract
  • changeAdmin updates the admin role to a new address.
  • changeAdmin may only be called by the admin role.
  • changeAdmin(address newAdmin) Interaction with FiatTokenProxy contract

configureController

  • configureController(controller, minter) - The owner assigns the controller to manage the minter. This allows the controller to call configureMinter, incrementMinterAllowance and removeMinter.
  • Note: configureController(controller, 0x00) is forbidden because it has the effect of removing the controller.
  • controller - each controller manages exactly one minter. A controller can enable/disable its minter, and modify the minting allowance by calling functions on the MasterMinter contract, and MasterMinter will call the appropriate functions on the minterManager.
  • When a controller calls a function on MasterMinter, the MasterMinter will call the appropriate function on the FiatToken contract on its behalf. Both the MasterMinter and the FiatToken do their own access control.
  • configureController(address _controller, address _worker) Interaction with MasterMinter contract
  • https://apothem.blocksscan.io/tx/0x17d854f2f13f1ef6d5769655c1d08c878246a66073e94196a11555f0c6922318

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configureMinter

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Other Function Summary

  • removeController(controller) - The owner disables the controller by setting its minter to 0x00.
  • setMinterManager(minterManager) - The owner sets a new contract to the minterManager address. This has no effect on the old minterManager contract. If the new minterManager does not implement the MinterManagementInterface or does not give this instance of the MasterMinter contract permission to call minter management functions then the controller calls to configureMinter, incrementMinterAllowance, and removeMinter will throw.
  • incrementMinterAllowance - A controller increments the allowance of an enabled minter (incrementMinterAllowance will throw if the minter is disabled). The MasterMinter contract will call the minterManager contract on the controller's behalf.
  • removeMinter - A controller disables a minter. The MasterMinter contract will call the minterManager contract on the controller's behalf.

Minting

A minter mints tokens via the mint method. The minter specifies the amount of tokens to create, and a _to address which will own the newly created tokens. A minter may only mint an amount less than or equal to its minterAllowance. The minterAllowance will decrease by the amount of tokens minted, and the balance of the _to address and totalSupply will each increase by amount.

minter - each minter is managed by one or more controller. The minter cannot perform any actions on the MasterMinter contract. It interacts only with the FiatToken contract.

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Transfer

  • Transfer function is used to transfer token from one address to another.
  • A blacklisted address will be unable to call transfer or transferFrom, and will be unable to receive tokens.
  • approve was not allowed for blacklisted addresses in FiatToken versions <2.2 but available in versions 2.2+. See "Blacklisting" section for more details.
  • transfer, transferFrom, and approve will fail if the contract has been paused.
  • transfer(address to, uint256 value) Interaction with FiatTokenV2_2 contract
  • https://apothem.blocksscan.io/tx/0xd851a277d3dd7b7026862b309f524714de4307ac39d166eeed885fb6a2c5cc1b

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Approve

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transferFrom

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Burning

A minter burns tokens via the burn method. The minter specifies the amount of tokens to burn, and the minter must have a balance greater than or equal to the amount. Burning tokens is restricted to minter addresses to avoid accidental burning of tokens by end users. A minter with a minterAllowance of 0 is allowed to burn tokens.
A minter can only burn tokens which it owns. When a minter burns tokens, its balance and the totalSupply are reduced by amount.

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Blacklisting

Addresses can be blacklisted. A blacklisted address will be unable to transfer tokens, mint, or burn tokens.

In FiatToken versions <2.2, A blacklisted address is unable to call approve, increaseAllowance, decreaseAllowance, or authorize future pull payments using permit. Nor can it be authorized to pull payments from other addresses. This has been changed in v2.2 where a blacklisted address can perform the above functions. But they are still blocked from transferring the assets in any way. and therefore any operations on modifying the allowance of blacklisted addresses are considered meaningless.

blacklister

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Adding a blacklisted address

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Removing a blacklisted address

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Pausing

The entire contract can be paused in case a serious bug is found or there is a serious key compromise. All transfers, minting, burning, and adding minters will be prevented while the contract is paused. Other functionality, such as modifying the blacklist, removing minters, changing roles, and upgrading will remain operational as those methods may be required to fix or mitigate the issue that caused Circle to pause the contract.

Pause

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Unpause

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Rescuer

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In conclusion, deploying the USDC stablecoin on the XDC blockchain opens up new avenues for stable and reliable transactions within the cryptocurrency ecosystem. With a clear understanding of the deployment process and the interaction dynamics outlined above, users can confidently navigate through the steps required to integrate this stablecoin solution.

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