🔐 Pi Blockchain Lock

A Raspberry Pi-powered smart lock simulation that uses blockchain authentication to control physical access — no cloud, no vendors, just trustless crypto-based security.

Instead of relying on centralized services like Ring, Nest, or Wi-Fi-based locks, this system uses Ethereum-compatible challenge-response signing and on-chain device registration to validate access before allowing the LED (simulating a lock) to toggle.

---

📦 Features

• 🔑 Challenge-response authentication with ECDSA private key
• 🔗 Ethereum-style smart contract for access control
• 📍 Ganache runs locally on the Pi (no internet needed)
• 💡 Raspberry Pi controls LED via GPIO (lock/unlock simulation)
• ❌ Unauthorized or unregistered devices are denied access
• 🧾 Access attempts logged in a local CSV file

---

🛠 Project Structure

File/Folder	Description
auth_check.py	Runs the lock logic and verifies device via signature
register_device.py	Registers a device address on-chain
deregister_device.py	Removes device from the smart contract
contract_abi.json	Contract ABI (copied from Remix)
contract_address.txt	Stores deployed contract address
device_key.txt	Contains the device’s Ethereum address and private key
access_log.csv	Logs of authentication attempts
DeviceAuth.sol	Solidity smart contract code

---

🧱 Hardware Requirements

• Raspberry Pi 3/4/Zero 2 W
• Breadboard
• 1x LED
• 1x Pushbutton
• 220Ω resistors (optional)
• Jumper wires

---

🚀 How It Works

1. Deploy a smart contract locally via Remix connected to Ganache
2. Register the device’s public Ethereum address on-chain
3. The Pi signs a random challenge using its private key
4. The signature is verified using the public address
5. If verified and registered, the LED toggles using the pushbutton

---

🔐 Why Use Blockchain?

• No central server to hack or fail
• Identity is proven via cryptography
• Revocation and auditing are native to the chain
• Real-world simulation of decentralized access control

---

⚙️ Setup Instructions

Install Python dependencies:

pip3 install web3 eth-account

Install and run Ganache on the Pi:

sudo npm install -g ganache
ganache

Deploy the smart contract:

1. Open Remix IDE on the Pi
2. Connect to http://127.0.0.1:8545 (Web3 provider)
3. Deploy DeviceAuth.sol
4. Save:
   • Contract address → contract_address.txt
   • ABI → contract_abi.json
   • Device address/private key → device_key.txt

---

🧪 Run the System

Register the device:

python3 register_device.py

Start the lock controller:

python3 auth_check.py

---

🗃 Sample Access Log

Example access_log.csv entry:

Time: 2025-04-18 14:52:30
Device Address: 0x729643A808Dac1Ef747f0F3dFb596F35c559754a
Transaction ID: 0xabc123...
Auth: SUCCESS

---

🧠 Future Improvements

• Add role-based access control (admin, guest, etc.)
• Use a secure element to store the private key
• Migrate to a real Ethereum testnet (e.g., Sepolia)
• Add a mobile/web frontend dashboard for access management
• Replace the LED with a solenoid, servo, or real lock

---

👨‍💻 Author

Alexander Segarra CIS 629 – Blockchain Systems
Syracuse University

---

🛡 License

This project is released under the MIT License — use it, learn from it, build on it.