Disable virtual serial port by default

[rossy]

It seems dangerous to leave this on. On Windows, at least, an unprivileged process can write to the serial port, and the debug interface could allow it to send privileged input or act as a keylogger.

Edit: Whoops. Somehow I missed the related issue #159 and pull request #160. I still believe the serial port should be off by default, at least until its security can be improved. It's important to note that keyloggers aren't the only threat. Sending fake input through the keyboard could be a problem too.

[haata]

Yeah, I agree with having the serial port disabled by default. At least for production keyboards.

I'm going to keep it enabled at least until I have the API working. Contemplating between rawhid and vendor specific. I know vendor specific will require a small driver (so it should be possible to harden on Windows), not sure about rawhid (which is the preferred interface when doing stuff like this). Do you have any thoughts on this?

[rossy]

That's a good question. I don't know if Windows allows unprivileged processes to send raw HID reports to vendor-defined devices, but I think it might. I have three vendor-defined devices on this PC at the moment and according to WinObj, their device objects allow write access for all users.