That's right, in fact if people remember that secret then it's not a "second factor" it's just another part of their password. A "factor" in the context of authentication means one of the various ways that can be used to verify someone's identity: "something you know" (password), "something you have" (non-duplicatable object, eg a SIM card or OTP token containing a secret that cannot be easily guessed or extracted), or "something you are" (biometrics).
Re:SMS is not 2FA-secure
by thaumasiotes on Saturday January 11, 2020 @03:13AM
(#22018833)
> in fact if people remember that secret then it's not a "second factor" it's just another part of their password.
This is more generous than it should be. Your TOTP secret is just another part of your password regardless of whether you personally remember it or not; what matters is that, if I would like to be you, I only need to know the secret.
But how do you protect access to the website - with a username and password? Or do people now need to remember another code like "JBSWY3DPEHPK3PXP" to set up the authenticator everytime they visit?
Mobile apps were one way to solve this although the hardware U2F tokens like Yubikey provide another authentication factor in a usable way (and more secure than TOTP because you can't be phished to enter them on the wrong site).