PHP SSO single sign-on implementation principle analysis

PHP SSO single sign-on implementation principle analysis

With the development of the Internet, people often encounter the need to log in again when using various websites and applications. problem, which not only wastes the user's time, but also brings inconvenience to the user. In order to solve this problem, SSO (Single Sign-On) technology came into being.

1. The concept of SSO single sign-on

SSO (Single Sign-On) is an authentication mechanism that allows users to log in only once in multiple associated applications. to access these applications. To put it simply, users only need to provide login credentials once and can seamlessly switch between multiple applications.

2. The implementation principle of SSO single sign-on

The roles required to implement SSO single sign-on include users, service providers (Service Provider, SP) and identity providers (Identity Provider, IdP). When a user logs in to an application for the first time, the system will perform identity authentication, then store the authentication result in the user's browser cookie, generate a unique identifier, and store this identifier in the application's database. . When the user accesses other applications, this identifier will also be sent to the service provider's server, and the service provider can authenticate based on this identifier to avoid repeated logins by the user.

Let’s use a specific example to understand the implementation principle of SSO single sign-on.

1. Create an Identity Provider (IdP)

An identity provider is the core system responsible for user authentication. First, we create a PHP file to implement the identity provider functionality.

<?php
session_start();
// 验证用户名和密码
function authenticate($username, $password) {
    // 进行身份验证逻辑
    if ($username === 'admin' && $password === '123456') {
        return true;
    }
    return false;
}

// 用户登录
function login($username, $password) {
    $authenticated = authenticate($username, $password);
    if ($authenticated) {
        $_SESSION['user'] = $username; // 将用户名存储在Session中
        return true;
    }
    return false;
}

// 用户注销
function logout() {
    unset($_SESSION['user']); // 清除Session中的用户信息
}

// 检查用户是否已登录
function checkLogin() {
    return isset($_SESSION['user']);
}
?>

2. Create a service provider (SP)

A service provider is an application system that relies on an identity provider to complete identity authentication. Similarly, we create a PHP file to implement the service provider functionality.

<?php
include 'idp.php'; // 引入身份提供商的文件

// 检查用户是否登录
if (!checkLogin()) {
    header("Location: login.php"); // 用户未登录则跳转到登录页面
    exit;
}

// 用户已登录，显示内容
echo "Welcome " . $_SESSION['user'];
?>

<a href="logout.php">Logout</a>

3. Create a page for user login

Create a login.php file in the service provider's directory for user login.

<?php
include 'idp.php';

// 处理用户提交的登录表单
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $username = $_POST['username'];
    $password = $_POST['password'];
    
    if (login($username, $password)) {
        header("Location: sp.php"); // 登录成功跳转到服务提供商页面
        exit;
    } else {
        echo "Invalid username or password";
    }
}
?>

<form method="POST">
    <input type="text" name="username" placeholder="Username" required><br>
    <input type="password" name="password" placeholder="Password" required><br>
    <button type="submit">Login</button>
</form>

4. Create user logout function

Create a logout.php file in the service provider's directory for user logout.

<?php
include 'idp.php';
logout(); // 用户注销
header("Location: login.php"); // 注销后跳转到登录页面
exit;
?>

3. Summary

SSO single sign-on, through the cooperation of identity providers and service providers, enables users to log in once and use it in multiple applications. During the implementation process, a suitable authentication mechanism needs to be adopted to ensure the security of login, and the identifier of the authentication result is saved in the system to facilitate authentication between various applications. The above is an analysis of the implementation principles of PHP SSO single sign-on. I hope it will be helpful to everyone.

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