Function in PHP for hashing passwords to be compatible with Mosquitto MQTT broker

mosquitto_pw.php

<?php

/**
 * @param string $plain
 * @param string $algo
 * @param int $iterations
 * @param int $saltlen
 * @param int $keylen
 * @return string
 */
function mosquitto_pw($plain, $algo = 'sha256', $iterations = 901, $saltlen = 12, $keylen = 24)
{
    $salt = base64_encode(openssl_random_pseudo_bytes($saltlen));
    $hash = hash_pbkdf2($algo, $plain, $salt, $iterations, $keylen, true);
    return sprintf('PBKDF2$%s$%d$%s$%s', $algo, $iterations, $salt, base64_encode($hash));
}