Multi-factor authentication (MFA-Authentification)

Multi-factor authentication

With multi-factor authentication, instead of just one factor for identity verification – comparable to a front door key, for example – a second factor is required, such as an additional numerical code that must be entered.

When authenticating on a website, for example, a password can serve as the first factor and a time-based one-time password (TOTP) generated by a second device can serve as the second factor.

This has the advantage that an attacker must obtain both factors if they want to authenticate themselves. These factors can be something only the user knows (password), something they possess (smartphone or token), or something they are (biometric data, such as fingerprints). The greater the separation between the first and second factors, the more secure multi-factor authentication is. Examples include a password stored in the user's memory that they only enter on their laptop and a TOTP generated by a specialised device that is not connected to a network.

It is dangerous to store or use the password on the same device that generates the TOTP (mobile phone).