prepare("SELECT password_hash FROM admin_users WHERE username = ?"); $stmt->execute([$user]); $row = $stmt->fetch(); if ($row && password_verify($pass, $row['password_hash'])) { session_regenerate_id(true); $_SESSION['admin_logged_in'] = true; $_SESSION['admin_user'] = $user; header('Location: index.php'); exit; } else { $error = 'Invalid username or password.'; // Slow down brute-force attempts sleep(1); } } } ?>