Captcha and Automatic generate Id Systems

Captcha.php

<?php

function generatekey()
{

$str="1234567890abcdefghijklmnopABCDEFGH";
$str2=substr(str_shuffle($str),0,5)
;
return $str2;
}
echo generatekey();

function uniq()

{
$key=uniqid();
return $key."hdfc";
}
echo uniq();
?>