Create UniqueID in php

function_genUUID.php

<?php
function genUUID($prefix=null,$maxlength=36)
{
    $s = strtoupper(
                    hash(
                         'whirlpool',hash('sha1',
                                          microtime(true).crypt(
                                                                uniqid(
                                                                       rand(),
                                                                       true)
                                                                )
                                          )
                         )
                    );
    $guidText =
        substr($s,0,8) . '-' .
        substr($s,8,4) . '-' .
        substr($s,12,4). '-' .
        substr($s,16,4). '-' .
        substr($s,20,$maxlength);
    return $prefix.$guidText;
}