This is an example dApp made with React.js to let users do transfers of a ConfidentialERC20 token on fhEVM. It contains also a button to request the decryption of an encrypted secret value.
You can either deploy the dApp on the real fhEVM coprocessor on the Ethereum Sepolia testnet, or on a local Hardhat node (i.e a mocked corpocessor).
First, before launching the React app, you must deploy the ConfidentialERC20 smart contract and mint the first few tokens.
To do this, go to the hardhat/ directory, and follow all the instructions from the README there to deploy and mint the first tokens with Alice's account, i.e until you are able to run the following command:
npm run deploy-sepolia
Note: Be careful to use your own private mnemonic key in this case, in the
.envfile (do not reuse the public values from.env.example!).
After you succesfully run the Sepolia deployment script, go to the frontend/ directory, and just run those two commands:
npm install
npm run dev
This will launch the front-end of the dApp from a local Vite server, which will be available at the following URL: http://localhost:4173/ . You can connect to the dApp with a Web3 wallet such as Metamask and start transferring tokens, reencrypt and read your balance, or request the decryption of the encrypted secret on Sepolia.
First go to the hardhat/ directory : define a new .env file - in mocked mode, simply doing a copy cp .env.example .env is doable, but you can also you your own private mnemonic - then install all packages with
npm i. Now you can launch the hardhat local node with:
npx hardhat node
This will also launch a mocked instance of the coprocessor.
You can then go to the frontend/ directory, and just run those two commands:
npm install
npm run dev-mocked
The dApp will be available again at: http://localhost:4173/ . You can connect to the dApp with a Web3 wallet such as Metamask and start transferring tokens, reencrypt and read your balance, or request the decryption of the encrypted. This time, the only difference is that it will ask you to connect to the Hardhat network instead of Sepolia, so make sure to have added the Hardhat network to your Metamask wallet in order to be able to use the dApp with the mocked coprocessor. You can find instructions to configure Metamask adequatly here.
Invalid nonce errors: This is a common issue everytime you restart your local Hardhat node and you want to reuse the same accounts in Metamask. You should remember to reset the nonce of the accounts you used the last time with Hardhat. To reset the account's transaction history and the nonce, open Metamask and select the Hardhat network, click on your account followed by Settings -> Advanced -> Clear activity tab data.