Google2FA

Google Two-Factor Authentication for PHP Package

Google2FA is a PHP implementation of the Google Two-Factor Authentication Module, supporting 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.

This package is agnostic, but also supports the Laravel Framework.

Requirements

• PHP 5.3.7+

Compatibility

You don't need Laravel to use it, but it's compatible with

• Laravel 4.1+
• Laravel 5+

Installing

Use Composer to install it:

composer require pragmarx/google2fa

Installing on Laravel

Add the Service Provider and Facade alias to your app/config/app.php (Laravel 4.x) or config/app.php (Laravel 5.x):

'PragmaRX\Google2FA\Vendor\Laravel\ServiceProvider',

'Google2FA' => 'PragmaRX\Google2FA\Vendor\Laravel\Facade',

Using It

Instantiate it directly

use PragmaRX\Google2FA\Google2FA;

$google2fa = new Google2FA();

return $google2fa->generateSecretKey();

In Laravel you can use the IoC Container and the contract

$google2fa = app()->make('PragmaRX\Google2FA\Contracts\Google2FA');

return $google2fa->generateSecretKey();

Or Method Injection, in Laravel 5

use PragmaRX\Google2FA\Contracts\Google2FA;

class WelcomeController extends Controller {

	public function generateKey(Google2FA $google2fa)
	{
		return $google2fa->generateSecretKey();
	}

}

Or the Facade

return Google2FA::generateSecretKey();

How To Generate And Use Two Factor Authentication

Generate a secret key for your user and save it:

$user = User::find(1);

$user->google2fa_secret = Google2FA::generateSecretKey();

$user->save();

Show the QR code to your user:

$google2fa_url = Google2FA::getQRCodeGoogleUrl(
	'YourCompany',
	$user->email,
	$user->google2fa_secret
);

{{ HTML::image($google2fa_url) }}

And they should see and scan the QR code to their applications:

And to verify, you just have to:

$secret = Input::get('secret');

$valid = Google2FA::verifyKey($user->google2fa_secret, $secret);

Server Time

It's really important that you keep your server time in sync with some NTP server, on Ubuntu you can add this to the crontab:

ntpdate ntp.ubuntu.com

Using a Bigger and Prefixing the Secret Key

Although the probability of collision of a 16 bytes (128 bits) random string is very low, you can harden it by:

Use a bigger key

$secretKey = $google2fa->generateSecretKey(32); // defaults to 16 bytes

Prefix it

$secretKey = $google2fa->generateSecretKey(16, $userId);

Demo

You can scan the QR code on this page with a Google Authenticator app and view the code changing (almost) in real time.

Google Authenticator Apps:

To use the two factor authentication, your user will have to install a Google Authenticator compatible app, those are some of the currently available:

• Authy for iOS, Android, Chrome, OS X
• FreeOTP for iOS, Android and Peeble
• FreeOTP for iOS, Android and Peeble
• Google Authenticator for iOS
• Google Authenticator for Android
• Google Authenticator for Blackberry
• Google Authenticator (port) on Windows app store

Tests

The package tests were written with phpspec.

Author

Antonio Carlos Ribeiro

License

Google2FA is licensed under the BSD 3-Clause License - see the LICENSE file for details

Contributing

Pull requests and issues are more than welcome.