Machine learning has become more and more powerful, to the point where a bad actor can take a photo and a voice
recording of someone you know, and forge a complete video recording. See the "OmniHuman-1" model developed by ByteDance:
Bad actors can now digitally impersonate someone you love, and trick you into doing things like paying a ransom.
To mitigate that risk, I have developed this simple solution where you can setup a unique time-based one-time passcode (TOTP) between any pair of persons.
This is how it works:
Note that this depends on both Alice's and Bob's phones being secure. If somebody steals Bob's phone and manages to bypass the fingerprint or PIN or facial recognition of Bob's phone, then all bets are off.
Source code of this page on GitHub