Andrey Ovcharov

Professional Software Engineer and hobbyist Hardware enthusiast

Andrey Ovcharov

URU Card - minimal FIDO2 implementation with Arduino

This update was delayed due to summer holidays but it brings achievement of the very important milestone. Now we have a very minimal implementation of the FIDO2 authentication protocol on the Arduino framework. The simplicity of the Arduino platform and the availability of the hardware opens the door to secure authentication to everyone interested.

The current state of the project

  1. I have implemented the basic Bluetooth Low Energy (BLE) communication profile.
  2. I have implemented GetInfo command so the server recognises the authenticator and starts the authentication process
  3. The very basic implementation of a command MakeCredential receives the data from the server and returns signed credential
  4. The command GetAssertion receives the credential and responds with confirmation of authentication.

The words “very basic” mean that many many features of the authentication flow are missing. For example, the private key is a simple hardcoded value and there are no real checks for user presence or user verification.

However, the project can be compiled, uploaded to the ESP32 development board and get “green” results in a simple test.

Results of URU Card online testing

How to run the project

So, what do you need to run the URU Card at home?

ESP32 development board and USB cable

You can use simple and affordable Wroom 32 development board. At the moment advanced features like secure element ATECC508a are not used so there is no need in more sophisticated boards.

Connect the board to your computer using USB cable and make sure the UART port is available to your system. Make sure the selected port provides enough current as the ESP32 chips are quite hungry and sensitive to stability of the power source.

Development Environment - PlatformIO

I am using a combination of Visual Studio Code and PlatformIO for the development. This combo gives ease of configuration, building and uploading the firmware to the board. Just follow installation instructions for your platform.

Windows machine or virtual environment

Despite the fact, the FIDO2 protocol supports BLE transport, at the moment is it available only under Windows. So, you will need either a Windows machine or a virtual environment. I am using Oracle Virtual Box and the trial version of Windows 10.

Building the project

First of all, get a copy of the source code using either git command or downloading a zip file from the project’s GitHub page.

Then, build the project and upload it to the development board using the following command in terminal (Mac OS/Linux):

pio run -t upload -monitor

The program will start immediately and the serial console will start output of the debug information.

Pairing the device

Open the Bluetooth settings in your Windows. Click the button “Add Bluetooth or other devices” and proceed with the pairing of the “URU Card”.

Example of pairing dialog window

After a few seconds, the device should be paired and appear in the list of available devices.

Running the test

Open the browser in your Windows. Chrome, Firefox and Edge browsers work equally well as they are using the system layer to communicate with the authenticator device. Visit the page and click the button “Create Credential”.

Setup URU Card in the browser

Just follow the key setup procedure and after a few seconds, a new credential will be generated by the device and sent to the browser.

The “Get Assertion” button will use a similar procedure to confirm the credential produced on the previous step.

The same procedure can be executed on page


The current state of the project provides a solid base to work on the fully-featured wireless FIDO2 authenticator device implemented with the Arduino framework. While the many crucial features are still missing, the existing ones provide a solid base to start playing with the technology.

If you have any questions regarding running the project on your development board or joining the development feel free to ask here in the comments section or directly using email or online messengers.