Two-Factor Authentication (2FA) Library

This PHP library provides functionality for generating Time-based One Time Passwords (TOTP) and HMAC-based One Time Passwords (HOTP), commonly used in two-factor authentication (2FA) systems.

Features

• TOTP Generation: Generate Time-based One Time Passwords.
• HOTP Generation: Generate HMAC-based One Time Passwords.
• Random Secret Key Generation: Generate random secret keys for use in TOTP and HOTP generation.

Usage

Install via composer:

composer require imseyed/auth2fa

TOTP Generation

The Auth2FA::TOTP method generates a Time-based One Time Password using the provided secret key and optional time slice. totp.example.php

$totp = imseyed\Auth2FA::TOTP($secret, $timeSlice);
/*
 $totp is a OPT code like: 458905
*/

If you want show expiration time of TOTP code must use Auth2FA::expire_time. that method return a number Unix timestamp.

$expirationTime = imseyed\Auth2FA::expire_time($timeSlice);
echo "Expire on ".date("H:i:s", $expirationTime)." (".($expirationTime - time())."s remind)";
/*
 $expirationTime is a unix timestamp like: 1722929683
*/

HOTP Generation

The Auth2FA::HOTP method generates an HMAC-based One Time Password using the provided secret key and counter value. hotp.example.php

$code = imseyed\Auth2FA::HOTP($secret, $counter);
/*
 $code is string like: 111222
*/

Secret Key Generation

The Auth2FA::generateSecret method generates a random secret key of the specified length.

$length = 16; // Secret key lenght
$secret = \imseyed\Auth2FA::generate_secret($length);
/*
 $secret is string like: OVZ7JFIPIXE4RTCE
*/

Note: There is no separate function to check the correctness of 2fa codes. You must use the generation functions to confirm the correctness of the codes sent by users.

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License

This library is released under the MIT License.