🎓 Blockchain Certificate Verifier

A decentralized, tamper-proof certificate verification system built on Ethereum. Institutions can issue certificates on-chain, and anyone can verify their authenticity instantly — no central authority required.

https://github.com/user/CertificateVerifier/assets/123456789/abc123-def456-ghi789

✨ Features:

• 🔒 Tamper-proof certificate issuance & verification
• 📄 Professional PDF certificate generation
• ☁️ IPFS storage via Pinata for decentralized file hosting
• 📱 QR codes for mobile verification
• 🌐 Works on Ethereum (local testnet or Sepolia)
• 💻 Responsive React.js frontend
• 🧪 Tested with Ganache & Truffle

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🚀 Live Demo

While this is a local dApp, you can run it on your machine in <5 minutes!
(Future: Deployed version coming soon on Sepolia + Vercel)

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🛠️ Tech Stack

• Smart Contract: Solidity 0.8.18 (Truffle)
• Frontend: React.js + Web3.js
• Backend: Express.js + Puppeteer (PDF generation)
• Storage: IPFS via Pinata API
• Blockchain: Ethereum (Ganache for local testing)
• Tools: Truffle, Ganache, MetaMask

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📦 Installation

Prerequisites

• Node.js (v16–v20 recommended)
• MetaMask browser extension
• Pinata Account (free tier works)
• Git

1. Clone the repo

git clone https://github.com/your-username/CertificateVerifier.git
cd CertificateVerifier

2. Install dependencies

# Install Truffle globally (if not already)
npm install -g truffle

# Install project dependencies
npm install

# Install React frontend dependencies
cd client
npm install
cd ..

3. Configure Pinata API Credentials

1. Go to Pinata and create a free account

2. Navigate to API Keys section

3. Click New Key and create an API key with pinning permissions

4. Copy your API Key and Secret

5. Create a .env file in the project root:

# Copy the example file
copy .env.example .env    # Windows
cp .env.example .env      # macOS/Linux

6. Edit .env and add your Pinata credentials:

PINATA_API_KEY=your_actual_api_key_here
PINATA_SECRET=your_actual_secret_key_here
PORT=3001
FRONTEND_URL=http://localhost:5173

⚠️ Important: Never commit your .env file to version control!

4. Start Ganache CLI

npx ganache

👉 Note: This starts a local blockchain on http://127.0.0.1:8545 (Chain ID: 1337)

Deployment

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1. Deploy smart contract

truffle migrate --reset --network development

2. Update frontend with contract ABI

# Windows (PowerShell)
Copy-Item build/contracts/CertificateVerifier.json client/src/contracts/

# macOS/Linux
cp build/contracts/CertificateVerifier.json client/src/contracts/

▶️ Run the Application

Terminal 1 - Start Backend Server:

node server.js

You should see:

🚀 Backend server running on http://localhost:3001
✅ Pinata API Key loaded: xxxxx...
✅ Pinata Secret loaded

Terminal 2 - Start Frontend:

cd client
npm run dev

3. Configure MetaMask

1. Add Custom Network

   Network Name: Ganache CLI

   RPC URL: http://127.0.0.1:8545

   Chain ID: 1337

2. Import account using the first private key from Ganache CLI output

4. Open in browser

👉 Go to http://localhost:5173

Usage

Issue a Certificate

1. Fill in Student Name, Course, and Email
2. Click "Issue Certificate"
3. Wait for PDF generation (takes ~5-10 seconds)
4. Confirm transaction in MetaMask
5. Download the PDF certificate from IPFS link

Verify a Certificate

1. Enter the same Email and Course
2. Click "Verify"
3. See certificate details with IPFS link
4. Scan QR code to verify on mobile

✅ All certificates are:

• Stored immutably on the blockchain
• Backed by PDF files on IPFS
• Verifiable via QR codes

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🔧 Troubleshooting

Backend Server Issues

Error: "PINATA_API_KEY is missing"

• Make sure you created a .env file in the project root
• Verify your Pinata credentials are correct
• Restart the server after adding credentials

Error: "ECONNREFUSED"

• Ensure the backend server is running on port 3001
• Check if another process is using port 3001

PDF Generation Issues

Error: "PDF generation failed"

• Puppeteer requires Chrome/Chromium to be installed
• On Windows, it should install automatically with npm install
• On Linux, you may need to install dependencies:

  sudo apt-get install -y chromium-browser

IPFS Upload Issues

Error: "Authentication failed"

• Double-check your Pinata API credentials
• Ensure there are no extra spaces in your .env file
• Try regenerating your API key on Pinata

Error: "Rate limit exceeded"

• Free Pinata accounts have rate limits
• Wait a few minutes before trying again
• Consider upgrading your Pinata plan for production use

MetaMask Issues

Transaction Fails

• Ensure you have enough ETH in your Ganache account
• Check that you're connected to the correct network (Ganache)
• Try resetting your MetaMask account (Settings → Advanced → Reset Account)

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📁 Project Structure

CertificateVerifier/
├── contracts/              # Solidity smart contracts
│   └── CertificateVerifier.sol
├── migrations/             # Truffle deployment scripts
├── client/                 # React frontend
│   └── src/
│       ├── App.jsx        # Main application component
│       └── contracts/     # Contract ABIs
├── server.js              # Express backend (PDF + IPFS)
├── .env                   # Environment variables (not in git)
├── .env.example           # Example environment file
├── package.json           # Backend dependencies
└── truffle-config.js      # Truffle configuration

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🚀 Future Enhancements

• Deploy to Sepolia testnet
• Batch certificate issuance
• Email notifications with certificate links
• Certificate revocation system
• Multiple certificate templates
• Admin dashboard for institutions
• Certificate analytics

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📝 License

MIT License - feel free to use this project for learning or production!!