Time-based One-time Password Algorithm (TOTP) auth plugin.
TOTP is an algorithm that computes a one-time password from a shared secret key and the current time.
TOTP is an implementation of a hash-based message authentication code (HMAC). It combines a secret key with the current timestamp using a cryptographic hash function to generate a one-time password. The timestamp typically increases in 30-second intervals, so passwords generated close together in time from the same secret key will be equal.