SSH authentication via Fingerprint scanning over network (SSL Sockets). This app stores your passphrase for the SSH key and when an authorized Fingerprint is scanned by the fingerprint sensor on the Android, it securely sends the passphrase via TLS Sockets to it's desktop counterpart, which then completes the SSH login!
The app is available on F-Droid: https://f-droid.org/en/packages/ro.ioanm.fissh/