Ah so you have numeric keys..
I use random strings like:
php Code:
function GetKey($length) {
$x=0;
$char = "abcdefghijklmnopqrstuvxyz=#1234567890-_";
$char_length = strlen($char);
$str = "";
while($x++ < $length) {
$str .= $char{rand(0,$char_length-1)};
}
return $str;
}