🏦 Bank Data Privacy Preservation System using Homomorphic Encryption

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📌 Abstract

A full-stack banking system that uses Paillier Homomorphic Encryption to keep account balances encrypted at all times — even during computation. Deposits, withdrawals, transfers, and portfolio analytics are performed directly on ciphertexts without ever decrypting individual balances. The backend is a Flask REST API secured with Firebase JWT authentication, and all encrypted data is stored in Firebase Firestore. A single-page web dashboard provides a complete banking interface.

Benchmarked at 100% decryption accuracy (₹0.000000 mean error), ~10ms per encrypt/decrypt, and 0.01ms for homomorphic addition.

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🚀 Project Setup

1. Clone & Install

git clone https://github.com/your-username/banking-he-system.git
cd banking-he-system
pip install flask flask-cors firebase-admin

2. Firebase Configuration

Backend — Download your service account key from Firebase Console → Project Settings → Service Accounts → Generate new private key. Save it as serviceAccountKey.json in the project root.

Frontend — Open templates/index.html and replace the placeholder Firebase config:

const firebaseConfig = {
  apiKey:            "YOUR_API_KEY",
  authDomain:        "YOUR_PROJECT.firebaseapp.com",
  projectId:         "YOUR_PROJECT_ID",
  storageBucket:     "YOUR_PROJECT.appspot.com",
  messagingSenderId: "YOUR_SENDER_ID",
  appId:             "YOUR_APP_ID"
};

Find these values at: Firebase Console → Project Settings → General → Your Apps.

3. Enable Firebase Services

In the Firebase Console, enable:

• Authentication → Sign-in method → Email/Password ✓
• Firestore Database → Create database (start in test mode) ✓

4. Run

python app.py

On first run, a 512-bit Paillier keypair is auto-generated and saved to data/keys.pkl. Open http://localhost:5000 in your browser.

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⚠️ Important

Add the following to your .gitignore before pushing:

serviceAccountKey.json   # Firebase private key — never commit
data/keys.pkl            # Paillier keypair — losing this makes all stored ciphertexts unreadable
__pycache__/
*.pyc
venv/

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📁 File Structure

├── app.py                          # Flask REST API + Firebase auth middleware
├── homomorphic_encryption.py       # Paillier HE implementation from scratch
├── paillier_performance_metrics.py # Benchmark suite
├── templates/index.html            # Web dashboard (Firebase Auth + Fetch API)
├── data/keys.pkl                   # Auto-generated keypair (gitignored)
└── serviceAccountKey.json          # Firebase service account (gitignored)