Google authenticator

$google = new GoogleAuthenticator();

// Register application
echo $google->getQRCodeUrl('MyApplicationName');

// Save secret Key
$secretKey = $google->getSecretKey();

$google = new GoogleAuthenticator($secretKey);

// User submit code
$userSubmitCode = '';

// Verify Code
if ($google->verifyCode($userSubmitCode)) {

    // OK
}