With two-factor authentication, we can access our sites with greater security than simply entering a username and password: in fact, each access will send us a code via SMS to be used together with credentials. If the SMS arrives late or is not received, we risk being left out of our account! To avoid this we can replace the sending of SMS with an authentication system using a disposable code ( OTP stands for One Time Password ), generated securely through some apps. In this guide we will show you the best apps to generate OTP for two-factor authentication, also explaining how to add the various accounts to be controlled to the app. At the end of the guide we will be able to obtain our OTP codes without having to wait for the SMS, quickly and safely, using an app uniquely associated with our mobile device.
READ ALSO: Secure authentication to access Facebook, Google, Amazon and other services
Enable two-factor authentication
Before we can use OTP codes, we will have to activate two-factor authentication on the site we want to protect with them. Among the most famous sites that accept OTP codes generated by apps for secure access, we recommend Amazon, LastPass, Microsoft, Google and Facebook, but hundreds of other sites are available that support this type of authentication. For each of these, the steps to follow are very similar to each other: we log in with the relevant account on the security page, enable two-factor authentication and choose to use an app-generated code (also called App code, Token code, Authenticator App or Authentication App ); at this point we will be offered a QR Code or a secret code, to be included in one of the apps that we will show you later in the article.
This code provided in the initial configuration phase is essential in order to correctly use the OTP code : in fact, the information contained within the QR Code or secret code allows you to generate a different password every few seconds, even without an Internet connection. By configuring the app, therefore, we will be able to access our account every time simply by entering the code displayed at the moment (possibly before the associated timer "expires"). To complete the configuration, simply enter the OTP code generated by the app immediately, so as to communicate the correct configuration to the site.
TECHNICAL NOTE : how the site and the app can communicate and know that the code is always correct, even without an Internet connection "> specific pseudo-random codes, based on the algorithm created for us by the service. Since the algorithm of the site (associated only with our account) and that of the app are identical, the generated OTP code will always be identical, therefore the site will always know what code to "expect" at that precise moment.
This authentication method is very secure and difficult for hackers and any attacker to intercept, since in order to violate it, you need to get your hands on the encrypted algorithm stored inside the app. The same apps offer very simple additional security systems, such as unlocking with the fingerprint: every time an OTP code is required, just open the app, use the fingerprint and retrieve the specific OTP code for the site to which we are accessing. In addition to the fingerprint, we can also set a PIN or password, in order to make access to the site even more difficult.
In case of loss of the phone or app, make sure to always activate an alternative two-factor authentication method (SMS, notification on the phone, call etc.), under penalty of the risk of remaining forever out of the account (since it will look for an OTP code that we can no longer generate).
If we want to deepen the discussion on two-factor authentication, we refer you to reading our dedicated guide -> Sites / apps where you can activate two-step password verification .
App to generate OTP
After seeing how to configure two-factor authentication, we will show you the apps that we can use to generate OTP codes. We remind you that these apps are suitable for all services that accept authentication via OTP: even if they seem specific to a service, they actually allow you to manage all the sites that support this type of authentication .LastPass Authenticator
One of the best apps to generate OTP is definitely LastPass Authenticator, available for free for Android and iOS.
With this app we can quickly scan QR codes or secret codes to add compatible services, including of course LastPass.
Once all the services have been added, we will have the numeric codes available on the same page, with a timer well displayed on the side of each site on which we have associated this type of authentication. To increase the security level of these codes, we can use a PIN, fingerprint or FaceID to quickly unlock the app.
This app works even if we have no account or password saved on LastPass, a famous service to securely store access passwords for our sites online, as seen in the dedicated article -> Memorize passwords and logins to websites in safe and secure way .
Microsoft Authenticator
Another app that we can use for authentication via OTP code is Microsoft Authenticator, available for free for Android and iOS.
This app allows you to immediately associate all the services that work with OTP codes, clearly and unambiguously showing the code generated at the time for a particular service. Again we can use fingerprints, Face ID or a simple PIN to protect access to codes for our accounts. To try absolutely as an alternative to the solution offered by LastPass (which I recommend to try anyway).
Google Authenticator
The Google app is one of the best for generating temporary OTP codes for use when two-factor authentication is enabled.For this app I had a separate guide on how to use Google Authenticator to secure web accounts
Authy
The last app that I recommend you try for authentication via OTP is Authy, which is also available for free for Android and iOS.
With a clear and simple to use interface, this app allows you to quickly associate the QR codes and secret codes of various services compatible with OTP authentication, with the possibility of copying the OTP generated also on the smartphone's notes, so as to use them to access the apps of the services on which we have activated authentication.
As with other apps, it offers the possibility to protect access to codes with PIN, fingerprint and Face ID, so as to keep intruders away.
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