How do I implement authentication and authorization in PHP?

authentication, authorization, PHP, PHP security, user management, web application security

This guide demonstrates how to implement authentication and authorization in PHP for securing web applications and managing user access levels.


            <?php
            // Start session and include database connection
            session_start();
            $pdo = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');

            // User registration
            function register($username, $password) {
                global $pdo;
                $hashedPassword = password_hash($password, PASSWORD_DEFAULT);
                $stmt = $pdo->prepare("INSERT INTO users (username, password) VALUES (?, ?)");
                return $stmt->execute([$username, $hashedPassword]);
            }

            // User login
            function login($username, $password) {
                global $pdo;
                $stmt = $pdo->prepare("SELECT * FROM users WHERE username = ?");
                $stmt->execute([$username]);
                $user = $stmt->fetch();
                if ($user && password_verify($password, $user['password'])) {
                    $_SESSION['user_id'] = $user['id'];
                    return true;
                }
                return false;
            }

            // Check if user is logged in
            function isLoggedIn() {
                return isset($_SESSION['user_id']);
            }

            // Authorization check
            function isAdmin() {
                global $pdo;
                if (!isLoggedIn()) return false;
                $stmt = $pdo->prepare("SELECT role FROM users WHERE id = ?");
                $stmt->execute([$_SESSION['user_id']]);
                $user = $stmt->fetch();
                return $user['role'] === 'admin';
            }

            // Example usage
            if ($_SERVER['REQUEST_METHOD'] === 'POST') {
                if (isset($_POST['register'])) {
                    register($_POST['username'], $_POST['password']);
                } elseif (isset($_POST['login'])) {
                    if (login($_POST['username'], $_POST['password'])) {
                        echo "Logged in successfully.";
                    } else {
                        echo "Login failed.";
                    }
                }
            }
            ?>

How do I implement authentication and authorization in PHP?

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How do I implement authentication and authorization in PHP?

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