README

• Copyright (c) 2012-2016, https://www.phpgangsta.de
• Author: Michael Kliewe, @PHPGangsta and contributors
• Licensed under the BSD License.

This PHP class can be used to interact with the Google Authenticator mobile app for 2-factor-authentication. This class can generate secrets, generate codes, validate codes and present a QR-Code for scanning the secret. It implements TOTP according to RFC6238

For a secure installation you have to make sure that used codes cannot be reused (replay-attack). You also need to limit the number of verifications, to fight against brute-force attacks. For example, you could limit the amount of verifications to 10 tries within 10 minutes for one IP address (or IPv6 block). It depends on your environment.

Supported PHP Versions

• PHP 8.0
• PHP 8.1
• PHP 8.2

Installation

composer req coderberg/google-authenticator

Usage

<?php

use Coderberg\GoogleAuthenticator;

$ga = new GoogleAuthenticator();
$secret = $ga->createSecret();
echo "Secret is: ".$secret."\n\n";

$qrCodeUrl = $ga->getQRCodeGoogleUrl('Blog', $secret);
echo "Google Charts URL for the QR-Code: ".$qrCodeUrl."\n\n";

$oneCode = $ga->getCode($secret);
echo "Checking Code '$oneCode' and Secret '$secret':\n";

$checkResult = $ga->verifyCode($secret, $oneCode, 2);    // 2 = 2*30sec clock tolerance
if ($checkResult) {
    echo 'OK';
} else {
    echo 'FAILED';
}

Running the script provides the following output:

Secret is: OQB6ZZGYHCPSX4AK

Google Charts URL for the QR-Code: https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=otpauth://totp/infoATphpgangsta.de%3Fsecret%3DOQB6ZZGYHCPSX4AK

Checking Code '848634' and Secret 'OQB6ZZGYHCPSX4AK':
OK