URU Card Brings FIDO2 Authentication to Your Wallet
A 2mm-thin ESP32-based Bluetooth authenticator with built-in keypad and OLED display
Self-proclaimed "hobbyist hardware enthusiast" Andrey Ovcharov wanted a Bluetooth FIDO2 authenticator, so he did what any self-respecting hacker would do: grabbed an ESP32 dev board and created a prototype. As he continued to iterate on the design, he added an ATECC508A secure element, and eventually a FPC1020AP capacitive fingerprint scanner. However, this presented an unexpected issue when attempting to open source the project: the fingerprint scanner required an NDA — plus the form factor was not particularly portable or robust anyway.
So Ovcharov reimagined the device as a credit card-sized PCB! Replacing the fingerprint scanner with a simple capacitive touch keyboard and MPR121 I2C touch sensor controller, removing the battery, and integrating a small OLED display and SSD1306 controller allowed the design to stay under 2mm and thus become completely wallet-able.
As we go to press, Ovcharov has implemented the BLE server and FIDO2 endpoints, but it is not yet fully functional. The PCB design is available for interested potential contributors, although anyone can reproduce the project using an ESP32 DevKit and the required parts. You can follow the URU Card's progress on Hackaday or on Ovcharov's blog.