QNetworkProxyFactory::setUseSystemConfiguration(true);

        QMessageBox::information(window(),
        tr("Information"),
        tr("Please select a folder with ca certificates."));
        //
        QString dir = QFileDialog::getExistingDirectory(
            this, tr("Open Directory"),
            QDir::homePath(),
            QFileDialog::ShowDirsOnly |
            QFileDialog::DontResolveSymlinks);

        if (dir.trimmed().length() < 2)
            dir = "/tmp";

        // ca certs ...
        QFileInfo fkey(QString("%1/ca.key.pem").arg(dir));
        QFileInfo fcrt(QString("%1/ca.crt.pem").arg(dir));

        if (!fkey.exists()) { QMessageBox::warning(window(),tr("Error"),tr("ca.key.pem not found.")); return; }
        if (!fcrt.exists()) { QMessageBox::warning(window(),tr("Error"),tr("ca.crt.pem not found.")); return; }

        QFile keyFile(QString("%1/ca.key.pem").arg(dir));
        QFile crtFile(QString("%1/ca.crt.pem").arg(dir));

        if (!keyFile.open(QIODevice::ReadOnly)) { QMessageBox::warning(window(),tr("ERROR"),tr("ca.key.pem not found.")); return; }
        if (!crtFile.open(QIODevice::ReadOnly)) { QMessageBox::warning(window(),tr("ERROR"),tr("ca.crt.pem not found.")); return; }

        const QByteArray keyBytes = keyFile.readAll();
        const QByteArray crtBytes = crtFile.readAll();

        if (keyBytes.trimmed().length() < 2) { msgError(1); return; }
        if (crtBytes.trimmed().length() < 2) { msgError(2); return; }

        QSslCertificate keyCert(keyBytes);
        QSslCertificate crtCert(crtBytes);

        QByteArray pass = "test";
        QSslKey privateKey(keyBytes,QSsl::Rsa,QSsl::Pem,QSsl::PrivateKey, pass);
        if (privateKey.isNull()) {
            QMessageBox::warning(window(),
            tr("Error"),
            tr("private key error."));
            return;
        }   else {
            QMessageBox::warning(window(),
            tr("info"),
            tr("private key ok"));
        }

        QSslConfiguration sslConfiguration;

        sslConfiguration.setPrivateKey(privateKey);
        sslConfiguration.setLocalCertificate(crtCert);
        sslConfiguration.setProtocol(QSsl::TlsV1_0);

        // fake test ...
        QNetworkAccessManager networkAccessManager;
        QNetworkRequest       networkRequest(QUrl("https://www.google.com/"));
        QNetworkReply *       networkReply
        = networkAccessManager.get(networkRequest);

        QEventLoop loop;
        QObject::connect(
            &networkAccessManager,
            &QNetworkAccessManager::finished,
            &loop,
            &QEventLoop::quit);
        loop.exec();

        if (networkReply->error() > 0) {
            QMessageBox::information(window(),tr("info"),
            QString("code: %1\nerror: %2")
            .arg(networkReply->error())
            .arg(networkReply->errorString()));
            delete networkReply;
            return;
        }

        delete networkReply;

        keyFile.close();
        crtFile.close();

        QMessageBox::warning(window(),
        tr("Error"),
        QString("cert: %1").arg(keyCert.expiryDate().toString()));
        return;