TOTP-PHP

Introduction

TOTP-PHP is a PHP library for generating Time-based One-Time Passwords (TOTP) for two-factor authentication. This library is easy to integrate into your existing PHP applications, allowing you to enhance your security measures effectively.

TOTP-PHP is compatible with Google Authenticator and other TOTP applications, making it a great choice for implementing two-factor authentication in your projects.

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.

Features

• Generate TOTP codes compliant with RFC 6238.
• Simple for use.
• Built-in validation methods.
• Secret key generation for TOTP.
• Compatible with Google Authenticator and similar apps.
• Generate QR code payloads for easy integration with TOTP applications.

Installation

You can install the totp-php library via Composer. Run the following command in your terminal:

composer require kayon-ariel/totp-php

Usage

Here is a simple example of how to use the library:

Generating a TOTP Code

require 'vendor/autoload.php';

use TotpPhp\Totp;

// Create a new TOTP instance
$ga = new Totp();

// Generate a secret key
$secret = $ga->createSecret();
echo "Secret is: " . $secret . "\n\n";

// Generate a TOTP code based on the secret
$oneCode = $ga->getCode($secret);
echo "Checking Code '$oneCode' and Secret '$secret':\n";

// Verify the TOTP code against the secret
$checkResult = $ga->verifyCode($secret, $oneCode);

if ($checkResult) {
    echo 'OK';
} else {
    echo 'FAILED';
}

Generating a Secret Key

You can generate a random secret key using the createSecret method. This is useful for initializing a new user or session.

$secret = $ga->createSecret();
echo "Your secret key is: " . $secret;

Generating a QR Code Payload

To generate a QR code payload for a TOTP secret, use the getQrCodePayload function:

$label = 'user@example.com'; // The user's email or username
$issuer = 'MyApp'; // Optional issuer name

$qrcodePayload = $totp->getQrCodePayload($secret, $label, $issuer);
echo "QR Code Payload: " . $qrcodePayload . "\n";

Validating a TOTP Code

You can validate a TOTP code using the verifyCode method:

$userInputCode = '123456'; // Example user input
$isValid = $ga->verifyCode($secret, $userInputCode);

if ($isValid) {
    echo "The TOTP code is valid!";
} else {
    echo "The TOTP code is invalid!";
}

Code Generation and Verification Logic

The library uses the following methods:

• createSecret(int $secretLength = 16): string: Generates a new secret key with a specified length (minimum 16 characters).
• getCode(string $secret, ?int $timeSlice = null): string: Calculates the TOTP code for a given secret key and time slice (defaults to the current time).
• verifyCode(string $secret, string $code, int $discrepancy = 1): bool: Checks if the provided TOTP code matches the expected code for the secret, allowing for some time discrepancy.

License

This library incorporates code from the original PHPGangsta/GoogleAuthenticator project:

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

Current: Copyright (c) 2024 Kayon Ariel, provided under the MIT License.

Contributions

Contributions are welcome! Feel free to submit issues, fork the repository, and submit pull requests.

Contact

For any inquiries or feedback, you can reach out to me at [kayonariel@gmail.com].