Common Types of 2FA
There are several types of two-factor authentication are in use today; some may be stronger or more complex than others, but all offer better protection than just a username and password.
The most popular form of two-factor authentication (and a preferred alternative to text messages) uses a software-generated time-based, one-time passcode.
First, a user must download and install a free 2FA app on their smartphone or desktop. They can then use the app with any site that supports this type of authentication. At sign-in, the user first enters a username and password, and then, when prompted, they enter the code shown on the app. Like hardware tokens, the soft-token is typically valid for 30 seconds. And because the code is generated and displayed on the same device, soft-tokens remove the chance of hacker interception. That’s a big concern with text message or voice delivery methods.
Best of all, since app-based 2FA solutions are available for mobile devices and computers, they even work offline so user authentication is possible just about everywhere, even in areas with poor network signal.
Probably the oldest form of 2FA, hardware tokens are small, like a key fob, and produce a new numeric code every 30-seconds. When a user tries to access an account, they glance at the device and enter the displayed 2FA code back into the site or app. Other versions of hardware tokens automatically transfer the 2FA code when plugged into a computer’s USB port.
They’ve got several downsides, however. For businesses, distributing these units is costly. And users find their size makes them easy to lose or misplace. Most importantly, they are not entirely safe from being hacked.
SMS-based 2FA interacts directly with a user’s phone. After receiving a username and password, the site sends the user a unique one-time passcode (OTP) via text message. Like the hardware token process, a user must then enter the OTP back into the application before getting access. Similarly, voice-based 2FA automatically dials a user and verbally delivers the 2FA code. While not common, it’s still used in countries where smartphones are expensive, or where cell service is poor.
For a low-risk online activity, authentication by text or voice may be all you need. But for websites that store your personal information — like utility companies, banks, or email accounts — this level of 2FA may not be secure enough. In fact, SMS is considered to be the least secure way to authenticate users. Because of this, many companies are upgrading their security by moving beyond SMS-based 2FA.
Rather than relying on the receipt and entry of a 2FA token, websites and apps can now send the user a push notification that an authentication attempt is taking place. The device owner simply views the details and can approve or deny access with a single touch. It’s passwordless authentication with no codes to enter, and no additional interaction required.
By having a direct and secure connection between the retailer, the 2FA service, and the device, push notification eliminates any opportunity for phishing, man-in-the-middle attacks, or unauthorised access. But it only works with an internet-connected device, one that’s able to install apps to. Also, in areas where smartphone penetration is low, or where the internet is unreliable, SMS-based 2FA may be a preferred fall-back. But where it is an option, push notifications provide a more user-friendly, more secure form of security.