In PHP, what are the advantages of using session IDs over storing user credentials in cookies for authentication purposes?

Using session IDs for authentication purposes is more secure than storing user credentials in cookies because session IDs are randomly generated and are not tied to the user's actual login information. This helps prevent unauthorized access to user accounts if the cookie is somehow compromised. Additionally, session IDs can be easily invalidated and regenerated, adding an extra layer of security to the authentication process.

// Start a new session or resume the existing session
session_start();

// Generate a random session ID
$session_id = bin2hex(random_bytes(32));

// Store the session ID in the session cookie
$_SESSION['session_id'] = $session_id;

// Validate the session ID before allowing access to restricted content
if ($_SESSION['session_id'] !== $session_id) {
    // Redirect to login page or deny access
    header('Location: login.php');
    exit();
}