Anyhow,if you wanted to make things harder for those who can,have and will again...simply take the publishers list of valid keys,brake them down into blocks and use a new SALT on each block.
not sure if you are talking about something else here altogether... the OP asked for whether a mod-apper could spoof/steal his own GUID and use it. so generating new keys is not the problem here 
Your smarter than that.
Make a Job out of it and run it with the next BE update.
Then again you now not have to decided not what GUID to global ban,but which whole BLOCK.
Now we all understand the bottom line here.
honestly, no idea what you are talking about here. i dont see how this relates to spoofing one specific GUID. i know, you think a mod-apper could spoof a whole block and get it banned, right? given that he can generate all these valid keys himself.
only one problem here: math behind keys doesnt matter much as gamespy simply has a list of all sold keys. so its great that you think you can generate a whole block of algo-valid keys, but that wont help much if those are not in the gamespy list
ive just read that and its absolute bollox bouncer , fish fish fish ..
if you stopped acting like you knew something and instead owned up to knowing nothing much , then maybe i would help you , nah actually maybe i wouldnt , truth im not too keen on you and thats a fact.
