Google Authenticator

KZero Staff
Oct 17, 2023

What is Google Authenticator?

Google Authenticator is an authenticator app used as part of a two-factor/multi-factor authentication (2FA/MFA) scheme. It acts as an example of a “something you have” factor by generating one-time passwords (OTPs) on a smartphone or other mobile device. When logging into a website or other account, a user will provide this OTP along with their password.

How Does 2FA/MFA Work?

Google Authenticator is designed to work as part of an MFA scheme. The goal of MFA is to enhance account security by requiring users to provide multiple different types of factors upon logging into their accounts. These factors generally come from one of three groups, including:

  • Something You Know: Knowledge-based factors include passwords, PINs, or the answers to security questions.
  • Something You Have: Possession-based factors include security tokens, smart cards, and smartphones.
  • Something You Are: Biometric factors include fingerprint, facial, voice, and gait recognition.

An MFA scheme requires factors from two or more of these three groups. Google Authenticator is an example of a “something you have” factor because OTPs are generated on the smartphone, and you need to have the smartphone to access these codes. Often, it is used to complement passwords as part of a 2FA scheme.

How Does Google Authenticator Work?

Google Authenticator generates time-based one-time passwords (TOTPs). When a user sets up MFA for an account, Google Authenticator will prompt them to scan a QR code or enter a security key. This creates a shared secret between the Google Authenticator app and the website.

Google Authenticator and the website use the same algorithm to generate a series of TOTPs. They start at the same place (that shared secret) and generate codes at regular intervals.

When a user wants to log into their account, they enter the TOTP currently displayed by Google Authenticator into the login page. The website will compare this value to the TOTPs that it has generated. Ideally, they should match, but sites will often accept one of the last few codes (to account for slow typing, etc.).

If the TOTP and the user’s password both match the server’s versions, then the user is authenticated and granted access. Otherwise, access is rejected, and the user may be prompted to try again to enter the password and/or TOTP.

Benefits of Google Authenticator

Google Authenticator is designed to make it easy for people to use MFA. Some of its benefits include:

  • Ease of Use: Support for QR codes makes it easy for a user to add a new account to their authenticator app.
  • Support for Multiple Accounts: The use of the TOTP protocol makes it possible for Google Authenticator to generate codes for a wide range of accounts.
  • Offline Generation: Google Authenticator doesn’t communicate with the website after initial account setup, so it can generate OTPs even when offline.
  • Enhanced Security: By enabling MFA, users make it more difficult for an attacker to gain access to their accounts.


Google Authenticator is an authenticator app designed to generate TOTPs for MFA. Its user-friendliness makes it a popular choice for people looking to improve the security of their online accounts.

KZero Staff

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