Google Authenticator is the open-source counterpart of Google’s one-time passcode apps, implementing industry-standard OATH algorithms such as TOTP (time-based) and HOTP (counter-based) for two-factor authentication. The repository historically hosts code for mobile platforms like iOS and BlackBerry, demonstrating how to generate numeric codes locally without needing network access. Its core purpose is to help services and users add a second factor that’s simple to deploy yet resistant to...