PHP에서 SSL을 사용하여 원격 MySQL 서버에 안전하게 연결하는 방법은 무엇입니까?

ini_set('error_reporting', E_ALL);
ini_set('display_errors', '1');
error_reporting(E_ALL|E_STRICT);

$db = mysqli_init();
mysqli_options($db, MYSQLI_OPT_SSL_VERIFY_SERVER_CERT, true);

$db->ssl_set('/etc/mysql/ssl/client-key.pem', '/etc/mysql/ssl/client-cert.pem', '/etc/mysql/ssl/ca-cert.pem', NULL, NULL);
$link = mysqli_real_connect($db, 'ip', 'user', 'pass', 'db', 3306, NULL, MYSQLI_CLIENT_SSL);
if (!$link) {
    die('Connect error (' . mysqli_connect_errno() . '): ' . mysqli_connect_error() . "\n");
} else {
    $res = $db->query('SHOW TABLES;');
    print_r($res);
    $db->close();
}

$pdo = new PDO('mysql:host=ip;dbname=db', 'user', 'pass', array(
    PDO::MYSQL_ATTR_SSL_KEY    => '/etc/mysql/ssl/client-key.pem',
    PDO::MYSQL_ATTR_SSL_CERT   => '/etc/mysql/ssl/client-cert.pem',
    PDO::MYSQL_ATTR_SSL_CA     => '/etc/mysql/ssl/ca-cert.pem'
));
$statement = $pdo->query("SHOW TABLES;");
$row = $statement->fetch(PDO::FETCH_ASSOC);
echo htmlentities($row['_message']);