True Random in PHP

true_rand.php

<?php
/**
 * Generate a true random integer.
 * To be used as a rand() replacement as it behave exactly the same.
 * 
 * int true_rand(void)
 * int true_rand(int $min, int $max)
 * 
 * It uses the HotBits webservice from FourmilLab as randomness provider
 * based on radioactive decay. See  https://www.fourmilab.ch/hotbits/.
 */
 
function true_rand($min=0, $max=null)
{
    $max = $max ?: getrandmax();
    $r = $max + 1 - $min;
    return abs(hexdec(bin2hex(file_get_contents(sprintf('https://www.fourmilab.ch/cgi-bin/Hotbits?nbytes=%d&fmt=bin&npass=1&lpass=8&pwtype=3', strlen(dechex($r)))))) % $r) + $min;
}