php 生成唯一的散列

function create_unique() {
    $data = $_SERVER['HTTP_USER_AGENT'] . $_SERVER['REMOTE_ADDR']
     .time() . rand();
    return sha1($data);
   
}

//生成的散列
if(isset($_COOKIE["userunique"])&&strlen($_COOKIE["userunique"])>10)
{
 $userunique=$_COOKIE["userunique"];
 setcookie("userunique",$userunique,time()+365*3600,"/");
}else
{
   $userunique = create_unique();
   setcookie("userunique",$userunique,time()+365*3600,"/",);
}

//cook的保存
$from_ip=$_SERVER['REMOTE_ADDR'];
echo $userunique;
echo "<br>";
echo $from_ip;

//$_SERVER服务器变量列表