Tasmota TLS Fingerprint Calculator

Tasmota is an open source alternative firmware for devices using ESP8266 and ESP32 microcontrollers. It allows local control using MQTT, with no dependencies on any cloud services. I use it with a number of home automation and environmental monitoring devices.

Even on my home network, I like to use TLS wherever possible. Tasmota supports connecting to MQTT servers using TLS, but resource constraints create challenges for certificate validation. Rather than checking for a signature from a trusted CA Tasmota can check the fingerprint of the server’s public key, similar to how SSH works.

If you want to explicitly configure a TLS fingerprint in Tasmota rather than using it’s “auto-learn” feature, you can paste your MQTT certificate below. The corresponding fingerprint will be calculated in your browser. No data is logged or even leaves your computer.

Please note that this is currently experimental, so make sure you test the fingerprint on a device you have physical access to.

There is also a command line version available.

Fingerprint00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00