Biometrics — like using your fingerprint as a password — is certainly convenient and are pretty commonplace on phones and laptops these days. While their overall security could be a problem, they certainly fit the bill to keep casual intruders out of your system. [Lewis Barclay] had some sensors gathering dust and decided to interface them to his Home Assistant setup using an ESP chip and MQTT.
You can see the device working in the video below. The code is on GitHub, and the only thing we worried about was the overall security. Of course, the security of fingerprint scanners is debatable since you hear stories about people lifting fingerprints with tape and glue, but even beyond that, if you were on the network, it would seem like you could sniff and fake fingerprint messages via MQTT. Depending on your security goals, that might not be a big deal and, of course, that assumes someone could compromise your network to start with.
On the other hand, this would probably work fine for keeping little ones out of the workshop or the liquor cabinet or something like that. If the kid can hack the MQTT, she probably should be in the workshop, after all. Seems like for real security, you’d need to authenticate the fingerprint reader with some sort of key scheme at a minimum.
If you want to know more about how fingerprint scanners work, there’s plenty to read about. If tape and glue are too low tech for you, you can also print a fake finger. That’s why we don’t suggest them for security.