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.

• 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.

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

$totp = Auth2FA::TOTP($secret, $timeSlice);
/*
 $totp is array like: ['code'=>111222, 'expire'=>1712003400];
*/

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

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

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

$length = 16; // Secret key lenght
$secret = Auth2FA::generateSecret($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.

This library is released under the MIT License.