HACKER Q&A
📣 rbrown

How do authenticator apps work?


Does anyone know how 2 factor authenticator services work? I'm curious how it's possible for the services reading them and the services creating them to predictably know the exact digit sequence at a given time without being knowable to 3rd parties. From an cursory undergraduate CS education it feels like a related but different problem to hash functions. Just curious!


  👤 cyb0rg0 Accepted Answer ✓
You click, tap and hope like hell, for the magic to happen

👤 pestatije
they sync with time

👤 jqpabc123
Each party (sender and receiver) has a secret key that they share.

This secret key is used by both send and receiver to encrypt the current time and produce a code.

If the codes match, you are authenticated; otherwise, you are not.