c++ load rsa key from file using crypto++

ding.cpp

template <typename Key>
const Key loadKey(const std::string& filename)
{
	Key key;
	CryptoPP::ByteQueue queue;
	CryptoPP::FileSource file(filename.c_str(), true);
	file.TransferTo(queue);
	queue.MessageEnd();

	key.Load(queue);
	return key;
}