Discord Interactions signature validation in native PHP 7.2+

interactions.php

<?php
$timestamp = $_SERVER['HTTP_X_SIGNATURE_TIMESTAMP'];
$signature = hex2bin($_SERVER['HTTP_X_SIGNATURE_ED25519']);
if ($signature === false) {
	die(http_response_code(403));
}
$publickey = hex2bin("[ YOUR_APP_PUBLIC_KEY ]"); // REPLACE THIS WITH YOUR OWN APP'S!
$postdata = file_get_contents('php://input');

// signature verification;
// requires PHP7.2+ compiled with sodium support and extension=sodium to be enabled in php.ini
$data_to_verify = $timestamp . $postdata;
if (sodium_crypto_sign_verify_detached($signature, $data_to_verify, $publickey) !== true) {
	die(http_response_code(403));
}

// parse your $postdata here...

?>