ApritiSedano is a secure, fully offline, Bluetooth Low Energy (BLE) based smart garage door opener. The project consists of a microcontroller unit (ESP32) that interfaces with the physical garage hardware, and a companion Android application to securely trigger the door and monitor its state.
- 100% Offline & Secure: No internet connection is required. The system relies entirely on BLE.
- TOTP-based Authentication: The Android app generates a Time-Based One-Time Password (TOTP) signed with HMAC-SHA1 to trigger the door. This prevents replay attacks and ensures only authorized devices can open the garage.
- Real-time State Monitoring: The MCU continuously broadcasts the garage door state (Open/Closed) via a non-connectable BLE Advertisement.
- Cryptographic State Integrity: The state beacon is signed with a time-based HMAC to prevent spoofing and replay attacks. The Android app mathematically verifies the state beacon before displaying it.
- Energy Efficient: Carefully optimized BLE scanning and advertising duty cycles on the ESP32 to prevent overheating and reduce power consumption.
- NFC & Voice Assistant Support: The Android app can be triggered automatically via NFC tags or Google Assistant shortcuts for a seamless "tap to open" or "voice to open" experience.
- Offline Timekeeping: Uses a DS3231 I2C RTC module on the ESP32 to maintain accurate time across reboots, which is critical for TOTP validation.
/MCU: The C++ source code for the ESP32 microcontroller. Built using the Arduino framework./ApritiSedano: The Android App source code (Java/Kotlin)./docs: Detailed documentation including the BLE Communication Protocol and Sequence Diagrams.apritisedano_case.scad: An OpenSCAD file for 3D printing a custom enclosure for the hardware.specs.md: The original detailed technical specifications and design choices for the project.
To build the MCU component, you will need:
- An ESP32 development board (e.g., Seeed Studio XIAO ESP32C6 or standard ESP32-WROOM-32).
- A 3.3V/5V Relay Module (to trigger the garage motor).
- A Magnetic Reed Switch / Sensor (to detect if the door is physically open or closed).
- A DS3231 RTC Module (for accurate offline timekeeping).
- Optional: LED and Piezo Buzzer for visual and auditory feedback.
Note: Pin configurations can be adjusted in MCU/HardwareConfig.h.
- Open the
MCUfolder in the Arduino IDE (or PlatformIO). - Install the necessary ESP32 board packages.
- In
HardwareConfig.h, uncomment the board you are using and verify the pinout. - Flash the code to your ESP32.
- On first boot, you can connect via Serial monitor and type
confto enter configuration mode. Here you can set the Base32 Secret Key (must match the one in the Android app) and sync the RTC time.
- Open the
/ApritiSedanofolder in Android Studio. - In
ApritiSedanoService.javaandMainActivity.java, ensure theSECRET_KEYmatches the one provisioned on your ESP32. - Build and install the APK on your Android device.
- Grant the required Location/Bluetooth permissions upon the first launch.
The communication between the phone and the garage door is strictly one-way during operation:
- To Open: The phone acts as a BLE Broadcaster (sending a 6-digit TOTP in the Manufacturer Specific Data). The ESP32 acts as a passive scanner, intercepts the packet, validates the TOTP against the shared secret and the current time, and triggers the relay.
- To Read State: The ESP32 acts as a BLE Broadcaster, transmitting a 10-byte payload containing the door state, a timestamp, and an HMAC-SHA1 signature. The phone scans for this beacon, verifies the signature using the shared secret, ensures the timestamp is strictly increasing (anti-replay), and updates the UI.
This architecture removes the need for slow BLE pairing/connections, making the response time near-instantaneous.
This project is open-source and available under standard open-source licenses. Please refer to individual components for specific licensing details.