dpraul / hardware-2fa

Implementation of TOTP on Arduino for 2FA with physical device.

Hardware-Device 2FA

Motivation

This project was created as a means to add location-based security by a dedicated 2FA device. I also did it for a school project, so check out [the report I wrote](Two-Factor Authentication with a Dedicated Hardware Device.pdf) for lots of extraneous words, pictures, libraries used, and extra info.

Hardware requirements

• Arduino Uno
• DS3231 RTC module: http://a.co/eDsdnLE
• MAX7219-driven 7-segment display matrix. Currently configured for this 8-digit matrix: http://a.co/1kaq6FC

Software requirements

• Arduino IDE: https://www.arduino.cc/en/Main/Software
• Python 3

Setup environment

1. Create a virtualenv: virtualenv env
   • if virtualenv isn't installed: pip install virtualenv
2. Activate the virtualenv: env\Scripts\activate (or, preface each command with env\Scripts\python)
3. Install dependencies: python -m pip install -r requirements.txt

Setup the TOTP secret

1. Choose a random 10-character ASCII password, for example: k30asvb6yd
2. Using the OTP tool at https://www.dylanpraul.com/tools/otp/
   1. Put whatever you want into the account name, for example: My App
   2. Enter your secret key into the box
   3. Click go
   4. Replace hmacKey[] in totp_interface\totp_interface.ino with the contents of the Arduino HEX array box. For example, k30asvb6yd results in {0x6b, 0x33, 0x30, 0x61, 0x73, 0x76, 0x62, 0x36, 0x79, 0x64}
   5. Copy your password to SECRET_PASSWORD in server\2fa.py
   6. Optionally, use the Google Authenticator app to scan the generated QRCode. This can be used to verify functionality later.

Setup the Arduino

1. Wire up the DS3231
   • GND to Arduino GND
   • VCC to Arduino 3.3V
   • SDA to Arduino A4
   • SCL to Arduino A5
2. Wire up the 7-segment displays (these can be changed in the top of totp_interface.ino)
   • GND to Arduino GND
   • VCC to Arduino 5V
   • DIN to Arduino D12
   • CLK to Arduino D11
   • CS/LOAD to Arduino D10
3. Connect the Arduino to a computer using a USB cable.
4. In the Arduino IDE, go to Tools--> Port--> Select the COM port that the Arduino UNO is listed in.
5. Replace port in sync_time\sync_time.py with the port (e.g. COM4) from the Arduino IDE
6. Also copy this port to port in server\2fa.py
7. Use the Arduino IDE to upload sync_time\sync_time.ino to the device.
8. Run env\Scripts\python sync_time\sync_time.py to set the RTC module to the current system time.
9. Use Arduino IDE to upload totp_interface\totp_interface.ino to the device.

The 7-segment display matrix should now be displaying the 6-digit TOTP.

Running the test server

An example Flask 2FA server is provided that can either match TOTP keys with the device or from a saved secret.

If the Arduino is connected to the computer, change USE_DEVICE_COMMUNICATION in server\2fa.py to True. Otherwise, leave it set to False. Enabling this feature allows the server to gather the 2FA token from the hardware device instead of by using the Python implementation.

1. Run cd server
2. Run python 2fa.py to start the server at http://127.0.0.1:5000
3. The password is password. Enter the displayed TOTP token to access secret.html