MedChain Vault Backend

This is the backend API for MedChain Vault – a secure, blockchain-powered platform for uploading, verifying, and managing Electronic Medical Records (EMRs) with on-chain access control.

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Features

• Secure File Upload: Receives EMRs, hashes files, uploads to IPFS, and logs file info to the smart contract.
• On-chain Audit Trail: Fetches all upload events for transparent history.
• Access Control: Lets file owners grant or revoke access to files for specific users (wallet addresses).
• Verification: Allows anyone with permission to verify a file’s authenticity and integrity.

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Stack

• Node.js (Express.js)
• Ethers.js (for smart contract interaction)
• Pinata (IPFS file storage)
• Multer (handling file uploads)
• dotenv (environment variables)

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Quick Start

1. Install Dependencies

npm install

2. Configure Environment

Create a .env file in /backend with these variables:

CONTRACT_ADDRESS=0xYourContractAddress
PRIVATE_KEY=your_private_key
RPC_URL=https://your_rpc_url
PINATA_API_KEY=your_pinata_api_key
PINATA_API_SECRET=your_pinata_api_secret

3. Start the Server

npm start

Server will run on http://localhost:5000 by default and hosted on https://medchainvaultbackend.onrender.com.

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API Endpoints

• POST /upload – Upload a file (needs MetaMask-signed hash, wallet address)
• GET /getFile/:hash – Get file record by hash (checks access)
• GET /auditTrail – Get list of uploaded files (from blockchain events)
• POST /grantAccess – Grant file access to a wallet address
• POST /revokeAccess – Revoke file access for a wallet address
• GET /canAccess/:fileHash/:address – Check if an address can access a file

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How It Works

1. Upload: User uploads a file and signs its hash with MetaMask. Server stores file on IPFS and logs metadata to blockchain.
2. Verify: Any user with access can verify a file’s authenticity using the blockchain.
3. Access Control: Only the uploader can grant/revoke access for others, enforced by the smart contract.

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Security Notes

• Never commit your .env or private key to GitHub!
• MetaMask signature is required for upload authentication.

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For Developers

• All smart contract interactions use Ethers.js.
• See index.js for implementation.
• Modify CORS if deploying frontend elsewhere.

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Credits

Built by Team Hack Demons for hackathons and innovation!