Inside Two-Factor Authentication Apps
Hackaday dives into the process of 2-Step Authentication. With the feeling that online security is constantly under attack many services are turning to 2-step to add an extra layer of safety. Even with the added protection make sure you have strong passwords. Read on to learn how they work and why they still aren’t fool proof. Via Hackaday:
Two-factor is great in theory. Instead of just relying on a password, “something you know” in the jargon, you combine another factor for authentication: “something you have” or “something you are”. Ideally, this means requiring possession of a cellphone or security token, or presenting your fingerprint to be scanned. In theory, there’s no difference between theory and practice.
In practice, because of cost and convenience, most 2FA implementations use an app that authenticates using the time-based one-time password (TOTP) algorithm. That is, it’s just another password. In particular, Google’s Authenticator app and the WordPress interface which I’m currently using implement “something I have” by storing this one-time password on my cellphone.
Remember that QR code on the screen when you enrolled your phone? That was the password. You could tell me this secret password, and then I’d know your account token too. With access to this initial password and a little code, I can log in without having a cell phone at all, much less yours. This is “something you know” rather than “something you have”. If you think this is semantics, let’s compare the security properties of SMS-based 2FA (which is 2FA) and app-based “2FA” which isn’t.
TOTP keys simply can’t be stored hashed, because the authentication algorithm requires them in raw form. When the TOTP key database gets compromised, all of the TOTP / 2FA protection becomes worthless and you’re relying on the strength of your password to save you. Until the database gets breached, however, the ever-changing TOTP password is a great protection against eavesdroppers.
Getting the best of both worlds is easy enough: use TOTP / 2FA when it’s available, but make sure that your passwords are unique across websites and that each one is long and strong. But don’t fool yourself into thinking that 2FA is a substitute for good password practices — you’ll be living just one database breach away from the edge.
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