Cabe Atwell writes on Hackster about Open Authenticator by Vedant Parajape which uses an ESP32 to secure data and features an OLED display, 300mAh LiPo battery, and a USB Type-C port for charging:
TOTP-Based Open Hardware Authenticator Powered by an ESP32 Microcontroller_
“I fired up google and tried to search about it, and surprisingly it used a pretty amazing concept. It had a shared key with the server, and then it did some computation on the shared key and current UTC time to get a 6-digit number. So, the remote device just had to be accurate at timekeeping,” Parajape noted in his project log. He then took that information and designed his initial Open Authenticator prototype using a development kit he had on hand and an ESP32 module. It worked well enough, but he wanted a more streamlined platform, similar to RSA’s SecureID Key FOB.
Some people like to use hardware authenticators or security keys when working with public or company computers to keep their data private, certainly so when hackers can easily steal unprotected information. There are many great authenticators on the market that can be had for cheap, but others such as developer Vedant Parajape have designed their own platforms using readily-available hardware. Parajape became interested in authenticators after seeing his dad’s security keys and wondered how they could generate code without being connected to a network.