What's the key byte code for 'ctrl'?

You can test yourself easily enough:

game.Players.LocalPlayer:GetMouse().KeyDown:connect(function(key) print(key,key:byte()); end);

For some reason for me it is giving 50 (which corresponds also to the 2 key for some reason?)

Ctrl is 50. In the future, if you need more byte codes, use this short script, it tells you the code of the keys you've pressed :

game.Players.LocalPlayer:GetMouse().KeyDown:connect(function(Key)
    print(string.byte(Key))
end)

I think it's 17, that's what I've gotten before.

This table has helped me SOOOO much with ASCCI codes: http://www.asciitable.com/