This is a simple implementation of dApp in react native using the MetaMask wallet and ethersjs.

We will create a certificate issue application for our a college. The mobile dApp will have the following feature:

• Issue Certificate - The authorized person will be able to issue the certificate
• Verify Certificate - Anyone can check the authenticity of the certificate and verify whether it was issued by the college
• View Certificate Details - the individual can access their certificate details from the system
• View Account Information - User will be able to see account address and its balance

In oder to try this app, follow the steps given below

git clone [email protected]:sumukus/gcitCert.git gcitCert
cd gcitCert
npm i

You have to edit the gcitCert.sol file.

• Inside the gcitCert.sol file replace the address in addgcitCert method with one of your MetaMask wallet account address from testnet(Sepolia)

require(msg.sender == address(0x9dC22219076ef89d9E0a6248F18B3582Ea7A93dB), "Only the authorized issuer can add certificates");

Then deploy the smart contract in the Sepolia testnet and take note of the contract address. We will require it later on to interact with the smart contract.

Create the .env file in the root directory and add the details for the given fields

SMART_CONTRACT_ADDRESS=Your smart contract address 
INFURA_API=infura api for your app
CERTIFICATE_ISSUER=address of certificate issuer

Now you can run the dApp using the command given below

npx expo start