Bob learned that his username and password for a popular game has been compromised. He contacts the company and resets all the information. The company suggests he use two-factor authentication…

A new username and password are both knowledge factors, so this is still single-factor authentication regardless of how strong the credentials are.

Two-factor authentication (2FA) requires presenting credentials from at least two different factor categories - knowledge, possession, or inherence. A fingerprint scanner provides an inherence factor (something you are), while a username and password provide a knowledge factor (something you know). Combining these two distinct categories fulfills the definition of 2FA and ensures that compromising one factor alone is not sufficient for access.

Using only a fingerprint scanner is still single-factor authentication (one inherence factor) with no second independent factor.

A username combined with a stronger password remains purely in the knowledge factor category and does not constitute two-factor authentication.