<?php

//生成唯一标识符   

//sha1()函数， "安全散列算法（SHA1）"   

function create_unique() {   

$data = $_SERVER['HTTP_USER_AGENT'] . $_SERVER['REMOTE_ADDR']   

.time() . rand();   

return sha1($data);   

//return md5(time().$data);   

//return $data;   

} 

//测试方法

   $newhash = create_unique();   

   echo $newhash;

//bc4941159eef2d06ad98df9c8ae00fa3a07fe7bc

?>