PHP implements authentication example through session control

PHP implements authentication example through session control_php example

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Release： 2023-03-02 22:46:02

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The idea of session control is to be able to track users based on a session on the website. The detailed code is compiled here, friends in need can refer to it.

Overview

http protocol is stateless. For each request, the server cannot distinguish the user. PHP session control gives the user a key (an encrypted session string), which is also a proof of the user's identity. The server stores the box (database, memory database or file) that can be opened by this key. The box contains the user's various variable information.

Traditional php session usage

<&#63;php
//page1.php 启动一个会话并注册一个变量
session_start();
$_SESSION['user_var'] = "hello,codekissyoung!";
//这里的可以将$_SESSION理解为用户的箱子，实际的实现是php在服务器端生成的小文件
&#63;>

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<&#63;php
//page2.php
session_start();
echo $_SESSION['user_var'];//通过钥匙访问自己的箱子内的变量
$_SESSION['user_var'] = "bey,codekissyoung!";
&#63;>

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<&#63;php
//page3.php 销毁钥匙,一般在用户注销时，访问page3.php文件
session_start();
session_destroy();
&#63;>

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Ask a question, where is the key? Didn’t you see the operation of giving the user the key?

This operation is done for us by PHP behind the scenes. Since you visit page1.php and run the program, session_start();, PHP will generate a PHPSESSID based on some conditions at the moment (user IP, browser number, time, etc.) After the variable, http response is returned to the client, the PHPSESSID is already stored in your browser cookie. Every time you visit this domain name again, the PHPSESSID will be sent to the server. This PHPSESSID is the user key I am talking about here.

One more question, the security of this PHPSESSID, is it easy to be stolen, is it easy to be forged, is it easy to be tampered with?

Using HTTPS can prevent tampering. Do not use PHPSESSID, but generate a secret key for the user to prevent forgery. As for whether it is easy to be stolen, there is really no research on it. For example, if your computer is connected to the Internet and hackers invade your computer.

Save the generated secret key in the browser cookie

Set cookies
setCookie('key','value',time()+3600);
Delete cookies
setCookie('key','',time()-1);

Achieve single sign-on: session sharing

Single sign-on: Multiple subsystems share a user authentication system. If you log in at one place, you can access all subsystems.

Imagine this scenario: Assume that the php environments of servers A and B are the same. The user got his key on server A, and then he took the key to access server B. Does he know server B?

Obviously not, the key generated by server A is not recognized by the server.

Solution: Regardless of whether the user accesses A or B, I store the generated key in C (the same database, or cache system). When the user accesses A or B again, both A and B will ask C: the user's key. Is the key right? If it is correct, the user can use the box stored in A or B.

<&#63;php
session_regenerate_id();//重置　session 　字符
$session_info=array('uid'=>$uid,'session'=>session_encrypt(session_id().time()));
//下一步将，$session_info 存到　C 中
&#63;>

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The following is an example of php implementing authentication through session control

Authentication application principal: authmain.PHP

<&#63;php 
//开启一个会话 
session_start(); 
 
if((!isset($userid))||(!isset($password))) { 
  $userid=$_POST['userid']; 
  $password=$_POST['password']; 
//连接数据库 
$db_conn=new mysqli("localhost", "root", "","auth"); 
if(mysqli_connect_errno()){ 
  echo '连接数据库失败：'.mysqli_connect_error(); 
  exit(); 
} 
//执行SQL查询语句 
$query="SELECT * FROM authorized_users WHERE name='".$userid."' and password=sha1('".$password."')"; 
$result=$db_conn->query($query); 
if($result->num_rows>0){ 
  //注册一个会话变量 
  $_SESSION['valid_user']=$userid; 
} 
//断开数据库连接 
$db_conn->close(); 
} 
&#63;> 
<!DOCTYPE html> 
<html> 
<head> 
  <meta charset="UTF-8"> 
  <title>身份验证</title> 
</head> 
<body> 
<h1>主页</h1> 
<&#63;php 
//判断用户是否已经登录 
if(isset($_SESSION['valid_user'])){ 
  echo $_SESSION['valid_user'].',您好，你已经登录'; 
  echo '<a href="logout.php">退出登录</a><br/>'; 
}else{ 
  if(isset($userid)){ 
    echo '您没有登录成功'; 
  }else{ 
    echo '您还没有登录<br/>'; 
  } 
  &#63;> 
  <form method="post" action="authmain.php"> 
    <p>用户名：<input type="text" name="userid"></p> 
 
    <p>密码：<input type="password" name="password"></p> 
 
    <p><input type="submit" name="submit" value="登录"></p> 
  </form> 
<&#63;php 
} 
&#63;> 
<br/> 
<a href="members_only.php">登录进入</a> 
 
</body> 
</html>

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Valid user check for website: members_only.php

<!DOCTYPE html> 
<html> 
<head> 
  <meta charset="UTF-8"> 
  <title>身份验证</title> 
</head> 
<body> 
<&#63;php 
//启用会话 
session_start(); 
 
echo '<h1>会员有效</h1>'; 
if(isset($_SESSION['valid_user'])){ 
  echo "<p>".$_SESSION['valid_user'].",您好，您已经登录成功</p>"; 
  echo '<p>会员可享受折扣优惠</p>'; 
}else{ 
  echo '<p>您还没有登录成功</p>'; 
  echo '<p>只有登录成功才能查看此页</p>'; 
} 
echo '<a href="authmain.php">返回主页</a>'; 
&#63;> 
</body> 
</html>

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Logout session variables and destroy session: logout.php

<&#63;php 
//启用会话 
session_start(); 
$olduser=$_SESSION['valid_user']; 
//注销会话变量 
unset($_SESSION['valid_user']); 
//销毁会话 
session_destroy(); 
&#63;> 
<!DOCTYPE html> 
<html> 
<head> 
  <meta charset="UTF-8"> 
  <title>退出登录</title> 
</head> 
<body> 
<h1>您退出登录了！</h1> 
<&#63;php 
if(!empty($olduser)){ 
  echo '退出登录了<br/>'; 
}else{ 
  echo '您没有登录过，所以当然也不存在退出登录<br/>'; 
} 
&#63;> 
<a href="authmain.php">返回主页</a> 
</body> 
</html>

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