I presumed they can be :) so my systems needs a text like this:
<machine nickname> <passcode>
It is on my todo list to improve this at some point - but not had chance yet.
<machine nickname> <passcode>
It is on my todo list to improve this at some point - but not had chance yet.
My message looks like this: <machine> <hashed passcode> <number>
The passcode is "hashed" with the number. When the server receives the message, it adds the number to a deny-list. That way, the number is only good for one use.
Also, the number has to conform to a certain pattern. I might change that to a pre-generated list of valid numbers, but for the moment, I can work out a valid number with pen and paper.
Not perfect, but I think it's good enough.