It remains available to the user, even if he does not have a mobile connection. To use it, you must first install one of these applications (for example, Google Authenticator , Twilio Authy , Duo Mobile , Yandex.Key ), and then select the option of double authentication through the application in the menu of the desir service. A QR code will appear on- and you can immiately use it. Many services (for example, VKontakte) also generate a number of backup codes for the user , which he can use if he does not have a mobile connection or loses his phone. To do this, you ne to print out these codes in advance or save them in a safe place.
The screen through this application
In addition there are several more types of login confirmation Singapore Phone Number List that are us less frequently: Physical security key : this device is in the form of a USB flash drive (for use with a smartphone, it is sometimes equipp with NFC and Bluetooth interfaces)  . Such a key can be us to enter the same social networks, but such a serious approach rather makes sense for storing very important data. Identity verification using biometrics. This method is not yet us in widespread services such as social networks. Does two-factor authentication guarantee absolute security Ideally.
This device with certain types of Trojan
The second login factor should come to the user on a USA CFO device other than the one from which the account is logg in,” says Denis Legezo, senior cybersecurity expert at Kaspersky Lab. – The risk appears when using the same device both to log into the account and to receive a one-time password. If the attackers were able to infects, then the one-time password would no longer be consider secure. But compar to the scenario where the user does not enable two-factor authentication at all, even the single device option looks incomparably better.” What if the second device is lost.