Google Authenticator: Difference between revisions
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==Technology== |
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Google Authenticator implements the [[time-based One-time Password Algorithm]] as defined in [[IETF]] RFC 6238, and the [[HOTP|HMAC-based One Time Password Algorithm]] as defined in [[IETF]] RFC 4226. |
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<!--16 character base32 code 10 byte secret key |
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unix epoch divided by thirty |
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hmac encode --> |
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==Open Source status on Android== |
==Open Source status on Android== |
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Revision as of 09:34, 31 July 2013
Google Authenticator is a software based two-step authentication token developed by Google. The Authenticator provides a six digit number users must provide in addition to their username and password to log into Google services. The Authenticator can also generate codes for third party applications, such as password managers or file hosting services. Some versions of the software are open source.
Implementation
Google provides Android,[1] BlackBerry and iOS,[2] versions of Authenticator. Several third party implementations are available.
- Windows Phone 7.5/8: Authenticator Virtual TokenFactor
- Windows Mobile: Google Authenticator for Windows Mobile
- Java CLI: Authenticator.jar
- Java GUI: JAuth
- J2ME: DS3 Oath gauthj2me lwuitgauthj2me Mobile-OTP (chinese only) totp-me
- PalmOS: gauthj2me
- Python: onetimepass
- PHP: GoogleAuthenticator.php
- Ruby: google_authenticator_auth gem (third party implementation)
- webOS: GAuth
- Windows: gauth4win MOS Authenticator
- .NET: TwoStepsAuthenticator
- HTML5: html5-google-authenticator
- MeeGo/Harmattan (Nokia N9): GAuth
- Apache: Google Authenticator Apache Module
- PAM: Google Pluggable Authentication Module oauth-pam
Technical description
The service provider generates an 80-bit secret key for each user. This is provided as a 16 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; or
- the counter that is incremented with each new code.
A portion of the HMAC is extracted and converted to a 6 digit code.
Pseudocode for Time OTP
function GoogleAuthenticatorCode(string secret)
key := base32decode(secret)
message := 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 until length of code is 6
return code
Pseudocode for Event/Counter OTP
function GoogleAuthenticatorCode(string secret)
key := base32decode(secret)
message := counter encoded on 8 bytes
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 until length of code is 6
return code
Open Source status on Android
The Authenticator app as available on Google's Android app market is proprietary, as explained on the project's development page:
"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."[3]
An independent fork of the Android version of the software named OTP Authenticator[4] has been created, which is based on the last version of the open source code that had been provided by Google.
Usage
Google Authenticator can be used for the following websites and applications:
- Amazon Web Services
- App.net[5]
- ArenaNet for access to Guild Wars and Guild Wars 2
- Bitstamp[6]
- Bitcoin.de
- Blockchain.info
- Coinbase
- Dashlane[7]
- DigitalOcean[8]
- Dreamhost control panel[9]
- Dropbox[10]
- Drupal (Plugin is needed)
- Evernote[11] Premium accounts initially, free accounts later
- Facebook[12]
- Gaia Online
- Google Apps
- Google Mail
- LastPass[13]
- Linode[14]
- LightDM / MDM / SSH (through libpam-google-authenticator)[15]
- Microsoft account
- Mt.Gox[16]
- Synology
- WordPress (S-CRIB OTP Authenticator or Google Authentication plugins needed)
- Xat
- XenForo (Add-on is needed)
References
- ^ Android version of Google Authenticator
- ^ iOS version of Google Authenticator
- ^ Open Source status of Google Authenticator on Android
- ^ OTP Authenticator, an Open Source fork of the Android app
- ^ Added security for your App.net account
- ^ UPDATE: BITSTAMP ADDS SUPPORT FOR TWO-FACTOR AUTHENTICATION
- ^ Dashlane Adds Two-Factor Authentication, a New Interface, and More (Lifehacker)
- ^ DigitalOcean Features
- ^ Enabling Multifactor Authentication
- ^ Dropbox with Google Authenticator
- ^ http://blog.evernote.com/blog/2013/05/30/evernote-talks-2-step-verification/
- ^ Use Facebook’s 2-factor Authentication with Third-Party TOTP Generators
- ^ LastPass with Google Authenticator
- ^ Linode Manager Two-Step Authentication
- ^ Login - Google Authenticator for Desktop (lightdm or gdm plugin) - Ask Ubuntu
- ^ Boost your account security thanks to Mt.Gox's new Security Center
External links
- Google Authenticator on Google Help
- Google Authenticator open source project on Google Code
- Google Authenticator implementation in Python on Stack Overflow
