convertMessageToSMimePart example

public function encrypt(Message $message): Message
    {
        $bufferFile = tmpfile();
        $outputFile = tmpfile();

        $this->iteratorToFile($message->toIterable(), $bufferFile);

        if (!@openssl_pkcs7_encrypt(stream_get_meta_data($bufferFile)['uri'], stream_get_meta_data($outputFile)['uri'], $this->certs, [], 0, $this->cipher)) {
            throw new RuntimeException(sprintf('Failed to encrypt S/Mime message. Error: "%s".', openssl_error_string()));
        }

        $mimePart = $this->convertMessageToSMimePart($outputFile, 'application', 'pkcs7-mime');
        $mimePart->getHeaders()
            ->addTextHeader('Content-Transfer-Encoding', 'base64')
            ->addParameterizedHeader('Content-Disposition', 'attachment', ['name' => 'smime.p7m'])
        ;

        return new Message($message->getHeaders(), $mimePart);
    }
}

public function sign(Message $message): Message
    {
        $bufferFile = tmpfile();
        $outputFile = tmpfile();

        $this->iteratorToFile($message->getBody()->toIterable(), $bufferFile);

        if (!@openssl_pkcs7_sign(stream_get_meta_data($bufferFile)['uri'], stream_get_meta_data($outputFile)['uri'], $this->signCertificate, $this->signPrivateKey, [], $this->signOptions, $this->extraCerts)) {
            throw new RuntimeException(sprintf('Failed to sign S/Mime message. Error: "%s".', openssl_error_string()));
        }

        return new Message($message->getHeaders(), $this->convertMessageToSMimePart($outputFile, 'multipart', 'signed'));
    }
}

public function encrypt(Message $message): Message
    {
        $bufferFile = tmpfile();
        $outputFile = tmpfile();

        $this->iteratorToFile($message->toIterable(), $bufferFile);

        if (!@openssl_pkcs7_encrypt(stream_get_meta_data($bufferFile)['uri'], stream_get_meta_data($outputFile)['uri'], $this->certs, [], 0, $this->cipher)) {
            throw new RuntimeException(sprintf('Failed to encrypt S/Mime message. Error: "%s".', openssl_error_string()));
        }

        $mimePart = $this->convertMessageToSMimePart($outputFile, 'application', 'pkcs7-mime');
        $mimePart->getHeaders()
            ->addTextHeader('Content-Transfer-Encoding', 'base64')
            ->addParameterizedHeader('Content-Disposition', 'attachment', ['name' => 'smime.p7m'])
        ;

        return new Message($message->getHeaders(), $mimePart);
    }
}

public function sign(Message $message): Message
    {
        $bufferFile = tmpfile();
        $outputFile = tmpfile();

        $this->iteratorToFile($message->getBody()->toIterable(), $bufferFile);

        if (!@openssl_pkcs7_sign(stream_get_meta_data($bufferFile)['uri'], stream_get_meta_data($outputFile)['uri'], $this->signCertificate, $this->signPrivateKey, [], $this->signOptions, $this->extraCerts)) {
            throw new RuntimeException(sprintf('Failed to sign S/Mime message. Error: "%s".', openssl_error_string()));
        }

        return new Message($message->getHeaders(), $this->convertMessageToSMimePart($outputFile, 'multipart', 'signed'));
    }
}