Swift_Signers_SMimeSigner::newInstance PHP Method

    public static function newInstance($certificate = null, $privateKey = null)
    {
        return new self($certificate, $privateKey);
    }

<?php

/**
 * 140-message-smime.php
 */
require_once '../vendor/autoload.php';
require_once './config.php';
$transport = Swift_SmtpTransport::newInstance(SMTP_HOST, SMTP_PORT);
$mailer = Swift_Mailer::newInstance($transport);
$message = Swift_Message::newInstance();
$message->setFrom(MAIL_FROM)->setTo(MAIL_TO)->setSubject('S/MIME signed mail')->setBody('This is a S/MIME mail');
// POINT of this sample
$smimeSigner = Swift_Signers_SMimeSigner::newInstance();
$smimeSigner->setSignCertificate(SMIME_CERT_FILE, [SMIME_SECRET_FILE, SMIME_SECRET_PASSPHRASE]);
$message->attachSigner($smimeSigner);
$result = $mailer->send($message);