> Keystroke timing has been a concern for terminal I/O since the 1980s and folks were using primitive encryption with stelnet and kerberos.

I had a visual basic AI addon in the 1990's that could work out who was typing at the keyboard from their typing pattern within a few minutes of typing, which kind of rendered the logon process mute.

Today, that can applied to touchscreen logons by tying finger pressure patterns ie size and shape of finger contact with the touchscreen to a user, and when incorporating swipes or mouse movements in the desktop OS context, its possible to have a security app which can lock a system if someone is using a device and user account which is not theirs.

At the very least you can log every time one's GF/missus has gone through your phone.