How to create secure https server in "Qt"? - c++

Question

I am going through the below github source code for implementation of rest server. It has details with respect to http server but when I am trying to create a secure server I am facing problem after adding the certificate and key. Please suggest how to establish a secure https server using Qt.
https://github.com/Tropby/QSimpleRestServer
QFile certFile("demo.cer");
QFile keyFile("demo.key");
QByteArray cert,key;
if(!certFile.open(QIODevice::ReadOnly))
{
qDebug() << "Couldn't Open Resource File.";
qDebug() << "Error: " << certFile.errorString();
}
else {
cert = certFile.readAll();
certFile.close();
}
if(!keyFile.open(QIODevice::ReadOnly))
{
qDebug() << "Couldn't Open Resource File.";
qDebug() << "Error: " << keyFile.errorString();
}
else {
key = keyFile.readAll();
keyFile.close();
}
if(sslSocket->setSocketDescriptor(socket_descriptor)){
qDebug()<<"set passed";
} else {
qDebug()<<"set failed";
}
sslSocket->setProtocol(QSsl::AnyProtocol);
sslSocket->ignoreSslErrors();
QSslKey ssl_key(key,QSsl::Rsa,QSsl::Pem,QSsl::PrivateKey,(QByteArray)"demo.key");
QSslCertificate ssl_cert(cert);
sslSocket->setLocalCertificate(cert);
sslSocket->setPrivateKey(ssl_key);
sslSocket->modeChanged(QSslSocket::SslMode::SslServerMode);
sslSocket->startServerEncryption();