Built for HackTX 2025

AuthLens is a blockchain-powered video authentication platform that ensures the integrity and verifiability of video evidence. By storing cryptographic hashes of video chunks on the Ethereum blockchain, AuthLens provides tamper-proof verification of video authenticity, timestamps, and ownership.

• 🔐 Blockchain-Backed Verification: Store cryptographic hashes on Ethereum for immutable proof
• ⏱️ Timestamp Validation: Track exact recording times for each video chunk
• 🎥 Chunked Processing: Process videos in 1-minute segments for efficient handling
• 🔍 Instant Verification: Quickly verify if a video exists on the blockchain
• 🌐 Decentralized Trust: Leverage blockchain technology for transparent, tamper-proof records

AuthLens/
├── contracts/              # Solidity smart contracts
│   └── VideoAuth.sol      # Main video authentication contract
├── backend/               # Python FastAPI server
│   ├── main.py           # API endpoints
│   ├── test_client.py    # Testing script
│   └── requirements.txt  # Python dependencies
├── AuthLens-Frontend/    # React frontend application
├── ignition/             # Hardhat deployment modules
├── test/                 # Smart contract tests
└── hardhat.config.ts     # Hardhat configuration

• Node.js (v18 or higher)
• Python (v3.8 or higher)
• MetaMask wallet with Sepolia testnet ETH
• Alchemy or Infura account for RPC access

npm install

Create a .env file in the root directory:

SEPOLIA_RPC_URL=https://eth-sepolia.g.alchemy.com/v2/YOUR_API_KEY
PRIVATE_KEY=your_wallet_private_key_here

⚠️ Security Note: Never commit your .env file or share your private key!

Deploy the VideoAuth contract to Sepolia testnet:

npx hardhat ignition deploy ignition/modules/Deploy.ts --network sepolia

After deployment, note the contract address displayed in the console. You'll need this for the backend configuration.

Check the deployment status:

npx hardhat ignition status chain-11155111

To verify the contract functionality:

npx hardhat test

cd backend

pip install -r requirements.txt

Create a .env file in the backend directory:

SEPOLIA_RPC_URL=https://eth-sepolia.g.alchemy.com/v2/YOUR_API_KEY
PRIVATE_KEY=your_wallet_private_key_here
CONTRACT_ADDRESS=your_deployed_contract_address_here

Copy the compiled contract ABI to the backend:

copy ..\artifacts\contracts\VideoAuth.sol\VideoAuth.json VideoAuth.json

Or on macOS/Linux:

cp ../artifacts/contracts/VideoAuth.sol/VideoAuth.json VideoAuth.json

python main.py

The server will start at http://localhost:8000

Open your browser and navigate to:

• API Documentation: http://localhost:8000/docs
• Health Check: http://localhost:8000/

The project includes a comprehensive test script to verify all functionality:

python test_client.py

This test script will:

1. ✅ Check server health
2. 📤 Upload video chunks with timestamps
3. 🔍 Verify videos on the blockchain
4. 📥 Retrieve videos from specific time ranges
5. ⏰ Test time range queries

You can also test individual endpoints using curl or the interactive API docs at http://localhost:8000/docs:

curl -X POST "http://localhost:8000/api/video/process-chunk?start_time=2025-01-15T10:00:00&end_time=2025-01-15T10:01:00" ^
  -F "video=@path/to/your/video.mp4"

curl -X POST "http://localhost:8000/api/video/verify" ^
  -F "video=@path/to/your/video.mp4"

curl "http://localhost:8000/api/video/range?start_time=2025-01-15T10:00:00&end_time=2025-01-15T11:00:00"

cd AuthLens-Frontend

npm install

npm start

The frontend will open at http://localhost:3000

The VideoAuth contract provides two main functions:

• storeHash(bytes32 _videoHash): Stores a video hash on the blockchain
• verifyHash(bytes32 _videoHash): Verifies if a hash exists and returns the uploader address

Problem: Contract deployment fails

• Solution: Ensure you have enough Sepolia ETH in your wallet (get free testnet ETH from Sepolia faucet)

Problem: Backend can't connect to contract

• Solution: Verify the CONTRACT_ADDRESS in your backend .env file matches the deployed contract address

Problem: Transaction reverts with "hash already registered"

• Solution: This video hash already exists on the blockchain - this is expected behavior for duplicate videos

This project is licensed under the MIT License.

Built with ❤️ for HackTX 2025

• Ethereum Foundation for blockchain infrastructure
• Hardhat for development tools
• FastAPI for the backend framework

After setting the variable, you can run the deployment with the Sepolia network:

npx hardhat ignition deploy --network sepolia ignition/modules/Counter.ts