PHP Class: `x_class_2fa`

The x_class_2fa class enables secure two-factor authentication (2FA) using time-based one-time passwords (TOTPs). It relies on a base64-encoded secret key to generate and verify short-lived codes, typically valid for 30 seconds. The default code length is 6 digits but can be adjusted using the $codeLength parameter. Accurate server time is essential to ensure proper code synchronization.

Use the class by including /_framework/classes/x_class_2fa.php.

Dependencies

PHP 7.1-7.4
PHP 8.0-8.4

PHP-Modules

session: Required if you plan to use sessions with 2FA. Ensure session support is enabled in your PHP configuration. Typically, PHP’s default installation includes this.
hashing: Required for cryptographic functions used in generating and verifying codes. Typically, PHP’s default installation includes this.

Methods

`__construct`

Initializes the 2FA class with a secret key and an optional code length.

Parameter	Type	Description	Default
`$secretKey`	string	The base64-encoded secret key used for generating and verifying 2FA codes.	None
`$codeLength`	int	The length of the 2FA code to be generated.	6

Return Value	When does this return value occur?
`void`	This is a constructor and does not return a value.

`generateSecretKey`

Generates a random secret key used for 2FA.

Parameter	Type	Description	Default
`$length`	int	The number of random bytes to generate before encoding.	16

Return Value	When does this return value occur?
`string` (base64-encoded)	Always returns a base64-encoded random string of the given byte length.

`generateCode`

Generates a time-based one-time password (TOTP) using the secret key.

Parameter	Type	Description	Default
None	—	This method takes no parameters.	—

Return Value	When does this return value occur?
`string`	Returns a TOTP code that is valid for a 30-second time window.

`verifyCode`

Verifies whether the provided code matches the currently valid 2FA code.

Parameter	Type	Description	Default
`$code`	string	The 2FA code to be verified.	None

Return Value	When does this return value occur?
`true`	If the provided code matches the generated code for the current time slot.
`false`	If the code is incorrect or expired.

Example

<?php
// Example of using the x_class_2fa class for generating and verifying 2FA codes

// Step 1: Initialize the 2FA class with a secret key (base64 encoded)
$secretKey = x_class_2fa::generateSecretKey(); // Generate a random secret key
$twofa = new x_class_2fa($secretKey);

// Step 2: Generate a 2FA code
$generatedCode = $twofa->generateCode();
echo "Generated 2FA Code: " . $generatedCode . "\n";

// Step 3: Verify the 2FA code
$isCodeValid = $twofa->verifyCode($generatedCode);
if ($isCodeValid) {
    echo "The 2FA code is valid.\n";
} else {
    echo "The 2FA code is invalid.\n";
}

// Step 4: Example of code expiration (simulate by checking if the code has changed after a delay)
sleep(30); // Wait for the code to expire (assuming 30-second expiration window)
$newGeneratedCode = $twofa->generateCode();
echo "New Generated 2FA Code after 30 seconds: " . $newGeneratedCode . "\n";
?>

PHP Class: x_class_2fa

Methods

__construct

generateSecretKey

generateCode

verifyCode