u/tsimmer_

Hi everyone!

I wanted to share my first embedded project. It's very similar to a yubikey! CyberKey is an open-source, fingerprint-protected hardware authenticator.

It stores your TOTP secrets securely and only reveals/types them after a successful fingerprint scan. Instead of just showing the code on the screen, it acts as a Bluetooth Keyboard. With one tap, it types your 6-digit OTP directly into your computer or phone.

The M5StickC Plus 2 was the perfect form factor. It’s pocketable, has a great display for the UI, and it's easy to integrate the fingerprint sensor. I wanted to build something that feels like a real-world "cyber" tool: utilitarian, secure, and futuristic.

Tech Stack:

• Hardware: M5StickC Plus 2 + Fingerprint Unit sensor from M5Stack.
• Language: Rust (ESP-IDF + no_std core logic).
• Crates: I’ve split the project into portable crates (TOTP engine, Fingerprint driver, HID tables) so they can be tested and reused easily.
• Custom UI: I implemented a custom proportional font system (using Orbitron) to give it a high-tech, functional aesthetic.

If you have any questions, don't hesitate!

The demo video is here: https://youtu.be/Q93ilcUGO0s

The code is here: https://github.com/thomassimmer/CyberKey

Hi everyone!

I wanted to share my first embedded project. CyberKey is an open-source, fingerprint-protected hardware authenticator.

It stores your TOTP secrets securely and only reveals/types them after a successful fingerprint scan. Instead of just showing the code on the screen, it acts as a Bluetooth Keyboard. With one tap, it types your 6-digit OTP directly into your computer or phone.

The M5StickC Plus 2 was the perfect form factor. It’s pocketable, has a great display for the UI, and it's easy to integrate the fingerprint sensor. I wanted to build something that feels like a real-world "cyber" tool: utilitarian, secure, and futuristic.

Tech Stack:

• Hardware: M5StickC Plus 2 + Fingerprint Unit sensor from M5Stack.
• Language: Rust (ESP-IDF + no_std core logic).
• Crates: I’ve split the project into portable crates (TOTP engine, Fingerprint driver, HID tables) so they can be tested and reused easily.
• Custom UI: I implemented a custom proportional font system (using Orbitron) to give it a high-tech, functional aesthetic.

If you have any questions, don't hesitate!

The demo video is here: https://youtu.be/Q93ilcUGO0s

The code is here: https://github.com/thomassimmer/CyberKey

Hi everyone!

I wanted to share a project I’ve been working on called CyberKey. It’s an open-source, fingerprint-protected hardware authenticator built using the M5StickC Plus 2 and the Fingerprint Unit.

It stores your TOTP secrets securely and only reveals/types them after a successful fingerprint scan. Instead of just showing the code on the screen, it acts as a Bluetooth Keyboard. With one tap, it types your 6-digit OTP directly into your computer or phone.

The M5StickC Plus 2 was the perfect form factor. It’s pocketable, has a great display for the UI, and it's easy to integrate the fingerprint sensor. I wanted to build something that feels like a real-world "cyber" tool: utilitarian, secure, and futuristic.

Tech Stack:

• Hardware: M5StickC Plus 2 + Fingerprint sensor.
• Language: Rust (ESP-IDF + no_std core logic).
• Crates: I’ve split the project into portable crates (TOTP engine, Fingerprint driver, HID tables) so they can be tested and reused easily.
• Custom UI: I implemented a custom proportional font system (using Orbitron) to give it a high-tech, functional aesthetic.

If you have any questions about running Rust on M5Stack or the biometric implementation, don't hesitate!

The demo video is here: https://youtu.be/Q93ilcUGO0s

The code is here: https://github.com/thomassimmer/CyberKey

I'm a software engineer, not a hardware engineer. But this game broke something in my brain. Every time I play, I'm thinking "wait, could this actually exist?".

A few weeks ago I finally found a project simple enough to start with, and useful enough to actually motivate me: I type an OTP code 5 times a day to connect to my work VPN. Every single time I have to grab my phone, open the authenticator, read the code, type it. It's such a small friction but it adds up.

So I built CyberKey: a small device with a fingerprint sensor. You enroll a finger, and from that point on: place finger → the 6-digit code is typed directly into your computer via Bluetooth. No phone, no app, no copy-paste.

It's not polished. The case is literally the original M5Stack enclosure. But it works, and every time I use it I feel like a cheap netrunner.

The demo video is here: https://youtu.be/Q93ilcUGO0s

The code is here: https://github.com/thomassimmer/CyberKey

I'm sharing this here because this community is the reason I started. I'd love your feedback and, I'm looking for ideas for what to build next. My long-term dream is to tackle things that exist in the game but not yet in real life. Hologram systems, brain-controlled interface, etc. What tech from the game do you wish existed IRL