<?php$valid_passwords = array ("user" => "password");$valid_users = array_keys($valid_passwords);$user = $_SERVER[‘PHP_AUTH_USER‘];$pass = $_SERVER[‘PHP_AUTH_PW‘];$validated = (in_array($user, $valid_users)) && ($pass == $valid_passwords[$user]);if (!$validated) {  header(‘WWW-Authenticate: Basic realm="My Realm"‘);  header(‘HTTP/1.0 401 Unauthorized‘);  die ("Not authorized");}// If arrives here, is a valid user.echo "<p>Welcome $user.</p>";echo "<p>Congratulation, you are into the system.</p>";