An open source USB module delivers fingerprint authentication to compatible Macs, offering a lower-cost alternative while supporting secure logins without replacing existing keyboards.
Developer Zimeng Xiong has introduced TinyTouch, an open source USB fingerprint authentication module designed for macOS that enables Touch ID-like authentication on compatible Macs without requiring Apple’s Magic Keyboard. The compact device offers users a more affordable way to add fingerprint-based login while keeping their preferred keyboards.
Housed in a small 3D-printed enclosure, TinyTouch combines an ESP32-S3 microcontroller, a UART fingerprint sensor with an integrated status light and a USB-C connection. The module is small enough to sit unobtrusively on a desk and works alongside an existing keyboard rather than replacing it.
Instead of attempting to replicate Apple’s proprietary Touch ID system, the project uses a practical approach based on the Personal Identity Verification (PIV) smart card standard already supported by macOS. During authentication, the computer sends a cryptographic challenge to the device, which signs it only after a successful fingerprint match, adding biometric verification before smart-card authentication.
The device supports two operating modes. HID mode behaves like a USB keyboard, retrieving an encrypted password from a helper application and entering it automatically after fingerprint verification. PIV mode avoids typing passwords altogether by relying on smart-card authentication, making it suitable for supported login and administrative functions such as sudo authentication.
The project also addresses security considerations. Communication between the fingerprint sensor and the microcontroller is currently unauthenticated, meaning physical access could theoretically allow spoofing attempts. To reduce this risk, the electronics are encapsulated in black epoxy to discourage tampering, while documentation recommends enabling secure boot and flash encryption on the ESP32-S3 to safeguard cryptographic keys.
Although the developer notes that Apple’s official Touch ID hardware remains the preferred option for high-security environments, TinyTouch provides an accessible open source alternative for enthusiasts seeking convenient fingerprint authentication on compatible Mac systems.
