🔐 zk-SNARKs Age Verification System

A privacy-preserving age verification system built with zk-SNARKs, enabling users to prove they are above a required age (e.g., 18+) without ever revealing their actual age.

This project demonstrates real cryptographic ZKPs — not just hashing tricks — using BN128 elliptic curves, bilinear pairings, and arithmetic circuits.

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✨ Features

• ✅ Zero-Knowledge: Server never learns your age
• ✅ Cryptographic Soundness: Proofs cannot be faked
• ✅ Succinct Proofs: Constant proof size (~1KB)
• ✅ Fast: Proof generation (~100ms), verification (~10ms)
• ✅ Non-Interactive: Only one message required
• ✅ Cloud Ready: Azure deployment templates included

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📖 How It Works

1. Client requests a challenge from the server
2. Client computes age locally (never sent to server)
3. zk-SNARK proof is generated using elliptic curve cryptography
4. Client sends proof only
5. Server verifies proof with bilinear pairings
6. ✅ Result: Server confirms “18+” without seeing actual age

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🧮 Example: Circuit Logic

```python``

Circuit: Prove age >= 18 without revealing age

def age_verification_circuit(private_age, public_minimum_age): difference = private_age - public_minimum_age return difference >= 0

ZKP/ ├── backend/ # Python backend │ ├── zksnark_main.py # FastAPI server │ ├── zksnark_age_verification.py # Core zk-SNARK implementation │ ├── main.py # Educational demo (for learning) │ └── requirements.txt # Dependencies (py_ecc, FastAPI) ├── frontend/ # Flutter frontend │ └── zkp_age_app/ │ ├── lib/main.dart # UI connected to API │ └── pubspec.yaml ├── azure/ # Azure deployment configs └── docs/ # Documentation

cd backend pip install -r requirements.txt python zksnark_main.py # Runs on http://localhost:8001

cd frontend/zkp_age_app flutter pub get flutter run -d web-server --web-port 3000

Access Points

🌐 Web App → http://localhost:3000

📚 API Docs → http://localhost:8001/docs

🔍 ZKP Info → http://localhost:8001/zkp-info

Security Properties

🤐 Zero-Knowledge: Age never revealed 🛡️ Soundness: Impossible to fake proof ✅ Completeness: Valid users always verified ⚡ Succinctness: Small, constant-size proofs

Backend → Azure App Service

az webapp create --resource-group myResourceGroup
--plan myAppServicePlan --name zksnark-backend
--runtime "PYTHON|3.11"

Frontend → Azure Static Web Apps

cd frontend/zkp_age_app flutter build web az staticwebapp create --name zksnark-frontend --source .

Backend tests

cd backend pytest -v

Flutter tests

cd frontend/zkp_age_app flutter test

This project is licensed under the MIT License. For educational and research purposes only.