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Revision as of 20:21, 30 March 2018
File:Google Authenticator for Android icon.png | |
Developer(s) | |
---|---|
Initial release | September 20, 2010[1] |
Repository | github |
Operating system | Android, iOS, BlackBerry OS |
Platform | Mobile |
License | Proprietary (earlier versions were under Apache License 2.0) |
Google Authenticator is a software token that implements two-step verification services using the Time-based One-time Password Algorithm (TOTP) and HMAC-based One-time Password Algorithm (HOTP), for authenticating users of mobile applications by Google. The service implements algorithms specified in RFC 6238 and RFC 4226, respectively.[2]
Authenticator provides a six- to eight-digit one-time password which users must provide in addition to their username and password to log into Google services or other sites. The Authenticator can also generate codes for third-party applications, such as password managers or file hosting services. Previous versions of the software were open-sourced but subsequent releases are proprietary.[3]
Typical use case
Typically, a user installs the Authenticator app on a smartphone. To log into a site or service that uses two-factor authentication, the user provides user name and password to the site and runs the Authenticator app. The app displays an additional six-digit one-time password. The same password is independently generated by the site, which asks the user for it. The user enters it, thus authenticating the user's identity.[citation needed]
For this to work, a set-up operation has to be performed ahead of time: the site provides a shared secret key to the user over a secure channel, to be stored in the Authenticator app. This secret key will be used for all future logins to the site.[citation needed]
With this kind of two-factor authentication, mere knowledge of username and password is not sufficient to break into a user's account. The attacker also needs knowledge of the shared secret key or physical access to the device running the Authenticator app. An alternative route of attack is a man-in-the-middle attack: if the computer used for the login process is compromised by a trojan, then username, password and one-time password can be captured by the trojan, which can then initiate its own login session to the site or monitor and modify the communication between user and site.[citation needed]
Implementations
Google provides Android,[4] BlackBerry, and iOS[5] versions of Authenticator. Several third party implementations are available.
- Windows Phone 7.5/8/8.1/10: Microsoft Authenticator[6] Virtual TokenFactor[7]
- Windows Mobile: Google Authenticator for Windows Mobile[8]
- Java CLI: Authenticator.jar[9]
- Java GUI: JAuth[10] FXAuth[11]
- J2ME: gauthj2me[12] lwuitgauthj2me[13] Mobile-OTP (Chinese only)[14] totp-me[15]
- Palm OS: gauthj2me[16]
- Python: onetimepass[17] pyotp[18]
- PHP: GoogleAuthenticator.php[19]
- Ruby: rotp,[20] twofu[21]
- Rails: active_model_otp[22] (third party implementation)
- webOS: GAuth[23]
- Windows: gauth4win[24] MOS Authenticator[25] WinAuth[26]
- .NET: TwoStepsAuthenticator[27]
- HTML5: html5-google-authenticator[28]
- MeeGo/Harmattan (Nokia N9): GAuth[29]
- Sailfish OS: SGAuth,[30] SailOTP[31]
- Apache: Google Authenticator Apache Module[32]
- PAM: Google Pluggable Authentication Module[33] oauth-pam[34]
- Backend: LinOTP (Management Backend implemented in python)
- Chrome/Chrome OS: Authenticator[35]
- iOS: Authy[36] Duo Mobile[37] OTP Auth[38]
- privacyIDEA Authentication System.
Technical description
The service provider generates an 80-bit secret key for each user (whereas RFC 4226 §4 requires 128 bits and recommends 160 bits).[39] This is provided as a 16, 26 or 32 character base32 string or as a QR code. The client creates an HMAC-SHA1 using this secret key. The message that is HMAC-ed can be:
- the number of 30-second periods having elapsed since the Unix epoch (TOTP); or
- the counter that is incremented with each new code (HOTP).
A portion of the HMAC is extracted and converted to a six-digit code.
Pseudocode for one-time password (OTP)
function GoogleAuthenticatorCode(string secret)
key := base32decode(secret)
message := floor(current Unix time / 30)
hash := HMAC-SHA1(key, message)
offset := last nibble of hash
truncatedHash := hash[offset..offset+3] //4 bytes starting at the offset
Set the first bit of truncatedHash to zero //remove the most significant bit
code := truncatedHash mod 1000000
pad code with 0 from the left until length of code is 6
return code
Open Source status on Android
As of September 16, 2017[update], the Google Authenticator app available on Google's Android app market is proprietary.[3] Google has made earlier source for their Authenticator app available on its GitHub repository. The project's development page states:
"This open source project allows you to download the code that powered version 2.21 of the application. Subsequent versions contain Google-specific workflows that are not part of the project."[33]
An independent fork of the Android version of the software named FreeOTP[40][3] has been created, which was based on the last version of the open source code that had been provided by Google, prior to their move to GitHub. A less popular fork named OTP Authenticator[41] is also available on Google Play.
References
- ^ "Google Is Making Your Account Vastly More Secure With Two-Step Authentication - TechCrunch". TechCrunch. 2010-09-20. Retrieved 2016-03-12.
- ^ "GitHub - google/google-authenticator: Open source version of Google Authenticator (except the Android app)". GitHub. Google.
These implementations support the HMAC-Based One-time Password (HOTP) algorithm specified in RFC 4226 and the Time-based One-time Password (TOTP) algorithm specified in RFC 6238.
- ^ a b c Willis, Nathan (22 January 2014)."FreeOTP multi-factor authentication". LWN.net. Retrieved 10 August 2015.
- ^ https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2 A
- ^ "Google Authenticator". App Store.
- ^ "Authenticator". 4 April 2013.
- ^ "Virtual TokenFactor". 26 February 2012.
- ^ "[APP]Google Authenticator for Windows Mobile". XDA Developers.
- ^ "http://blog dot jamesdotcuff dot net".
- ^ "mclamp/JAuth". GitHub.
- ^ "kamenitxan/FXAuth". GitHub.
- ^ "gauthj2me - Google Authentification in Java Mobile, j2me - Google Project Hosting".
- ^ "lwuitgauthj2me - Google Authenticator for J2ME phones - Google Project Hosting".
- ^ "chunlinyao / mobile-otp — Bitbucket".
- ^ "totp-me - TOTP for Java ME - Google authenticator".
- ^ "gauth.prc - gauthj2me - Google Authenticator for Palm OS (converted from java) - Google Authentification in Java Mobile, j2me - Google Project Hosting".
- ^ "tadeck/onetimepass". GitHub.
- ^ "pyotp/pyotp". GitHub.
- ^ "chregu/GoogleAuthenticator.php". GitHub.
- ^ "rotp - RubyGems.org - your community gem host".
- ^ "ukazap/twofu". GitHub.
- ^ "heapsource/active_model_otp". GitHub.
- ^ "GAuth".
- ^ "gauth4win - Google Authenticator for windows - Google Project Hosting".
- ^ "MOS Authenticator Home".
- ^ "winauth - Windows Authenticator for Battle.net / World of Warcraft / Guild Wars 2 / Glyph / WildStar / Google / Bitcoin - Google Project Hosting".
- ^ "glacasa/TwoStepsAuthenticator". GitHub.
- ^ "gbraad/html5-google-authenticator". GitHub.
- ^ Techtransit. "Nokia Store: Download GAuth and many other games, wallpaper, ringtones and mobile apps on your Nokia phone".
- ^ "SGAuth".
- ^ "SailOTP".
- ^ "google-authenticator-apache-module - Apache Module for Two-Factor Authentication via Google Authenticator - Google Project Hosting".
- ^ a b "google-authenticator - Two-step verification - Google Project Hosting".
- ^ "oauth-pam - PAM for use with OAuth Websites - Google Project Hosting".
- ^ "Authenticator".
- ^ "Authy". App Store.
- ^ "Duo Mobile". App Store.
- ^ "OTP Auth". App Store.
- ^ https://tools.ietf.org/html/rfc4226#section-4
- ^ "FreeOTP".
- ^ "kaie/otp-authenticator-android". GitHub.
External links
- Google Authenticator on Google Help
- Google Authenticator (Android) and Google Authenticator (other) legacy source code on GitHub
- Google Authenticator PAM module source code on GitHub
- Google Authenticator implementation in Python on Stack Overflow
- Authenticator on F-Droid
- Django-MFA Implementation Using Google Authenticator - Django-mfa is a simple package to add extra layer of security to your django web application. It gives web app a randomly changing password as an extra protection.