Google Authenticator is an application that implements Time-based One-time Password Algorithm (TOTP) security tokens in mobile apps made by Google.The Authenticator can also generate codes for third-party applications or file hosting services.Previous versions of the software were open source but subsequent releases are proprietary.
The service provider generates an 80-bit secret key for each user (in contravention of RFC 4226 §4). This is provided as a 16, 24 or 32 character base32 string or as a QR code. The client creates an HMAC-SHA1 using this secret key.
users will install the Authenticator app on their smartphone to log into a site or service that uses two-factor authentication, they provide user name and password to the site and run the Authenticator app which produces an additional six-digit one-time password. The user provides this to the site, the site checks it for correctness and authenticates the user.
How to two-step authentication is enabled for your Google account
1.Make sure that two-step authentication is enabled and configured for your account.
2.Download and install the app on your Android device or on your iPhone, iPad or iPod Touch
3.Login to your Google account at http://accounts.google.com. Choose “Security” from the left-side menu, then look for “2-step verification” and click “Edit”. You may need to login again.
Connect your Google Authenticator app to your Google account by following the prompts after “How to Connect” a Mobile Application.
Install Google Authenticator