ERC-20 Sybil Token

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Overview

An ERC-20 is the technical standard for fungible tokens in the Ethereum blockchain, a fungible token is interchangeable with another tokens. By following standards tokens have a property that makes them exactly the same.

ERC-20 Content

The standard list a series of functions (called method in the ERC) and events that must be implemented in order for the token to be ERC-20 compliant.

The functions are:

• approve: Allows an spender to withdraw tokens from a specific account, up to a specific amount.
• transfer: Execute the transfer of an amount of tokens from an account to another account.
• balanceOf: Reads the balance of tokens that an account holds.
• allowance: Returns a set number of tokens to a spender from an owner.
• totalSupply: Returns the current amount of tokens in circulation.
• transferFrom: Execute the transfer of tokens from a specific account to another account using the allowance of a spender.

The events are:

• Approve: A log of an approved event. Contains the account approved and its allowance.
• Transfer: A event triggered when a transfer is successful.

The following functions are not required but enhance token usability:

• name: The name of the token.
• decimals: Returns the number of decimals of the token.
• symbol: Reads the symbol of the token.

Contracts of the project

• SybilToken.sol: contract of the token, the initial supply is 1,000,000,000 tokens The supply will be reduced every 24hrs by the burner contract until it reaches the target supply of to 500,000,000 tokens. This token is ERC-20 compliant.

• SybilFaucet.sol: Allots 10 SYL tokens per request every 10 minutes.

• SybilBurner.sol: Using Chainlink Automation, this contract removes 137,000 tokens from circulation every 24hrs.

Quick Start

Clone this repo and cd into the folder:

git clone https://github.com/PacelliV/erc-20-sybil-token.git
cd erc-20-sybil-token

Run yarn to install all the dependencies:

yarn

Test Locally

Compile

Compile the project, mocks and inherited contract with:

yarn hardhat compile

Deploy

Deploy the project, mocks and inherited contract with:

yarn hardhat deploy

Test

Extensive and comprehensive unit tests against the contracts of this project has been provided. Run:

yarn hardhat test

Coverage

This project has a 100% of coverage over the functions of the contracts.

yarn hardhat coverage

Testing on Göerli

1. Set up environment variables:

You'll need to set your RPC_URL_GOERLI and PRIVATE_KEY_A as enviroment variables. You can add them to an .env file.

• PRIVATE_KEY: The private key of your account (e.g. from Metamask). NOTE: IT IS RECOMMENDED TO CREATE A NEW ACCOUNT FOR TESTING PURPOSES AND NEVER USE AN ACCOUNT WITH REAL FUNDS.
  • You can learn how to export a private key here.
• RPC_URL_GOERLI: I'ts the url of the goerli node you are working with. You can set up one for free in Alchemy.

2. Get test ETH and LINK

Go to https://goerlifaucet.com/ or faucets.chain.link to get test ETH and LINK in your Metamask.

Once you've requested for LINK tokens, this are not visible by default on Metamask, in order to see the balance of this token you'll need to import it. Read more about how to set up your wallet with LINK.

3. Deploy to Göerli:

yarn hardhat deploy --network goerli

4. Default values:

Some values has been provided as default for the contructors of the contracts, but you're welcome to change the ones that are not immutable.

5. After deploying, the faucet has zero tokens in its balance. Send tokens to it by using the fund-faucet task from the task folder.

6. Call the approve method to set SybilBurner.sol as a spender of tokens, use the approve-burner task to set an allowance.

7. Register SybilBurner.sol contract in Chainlink Automation.

The process of burning tokens in SybilBurner.sol is automated with Chainlink Automation. In order for Chainlink Nodes to be checking for our contract to know if they have to call performUpkeep we need to create an upkeep.

Read more to find extra information.

Go to automation.chain.link and register a new upkeep. Choose Custom logic as the trigger mechanism for the upkeep and insert your contract address. Fund the upkeep with 8 LINK.

8. Once you registered the upkeep, SybilBurner.sol will start burning 10,000 tokens every 24hrs. The upkeep will not run if the balance goes to zero, remember to check its balance from time to time.

Estimate gas cost in USD

To get an USD estimation of gas cost, you'll need a COINMARKETCAP_API_KEY environment variable. You can get one for free from CoinMarketCap.

Then, uncomment the line coinmarketcap: COINMARKETCAP_API_KEY, in hardhat.config.js to get the USD estimation. Just note, everytime you run your tests it will use an API call, so it might make sense to have using coinmarketcap disabled until you need it. You can disable it by just commenting the line.

Verify on Etherscan

If you deploy your contracts to a testnet or mainnet, you can verify them if you get an API Key from Etherscan and set it as an environemnt variable with the name ETHERSCAN_API_KEY. You can pop it into your .env file as seen in the .env.example.

However, you also can manually verify with:

yarn hardhat verify <DEPLOYED_CONTRACT_ADDRESS> --constructor-args

In it's current state, if you have your api key set, it will auto verify contract deployed on Göerli.

Typescript

There's no typescript version of this repo, but PRs are welcome!

Linting

To check linting / code formatting:

yarn lint

or, to fix:

yarn lint:fix

Resources 📚

• Hardhat docs
• ERC-20: Token Standard
• Chainlink Automation
• Ethers.js docs

Outro ⭐️

I hope you like this project and it ends up being useful to you. 👩🏻‍💻 👨🏻‍💻🎉 🎉