(OT) lincense protection generator

John Machin sjmachin at lexicon.net
Fri Jun 3 02:26:52 CEST 2005

flupke wrote:
> I'm going to be distributing a program based on wxPython & python in a 
> few weeks time. The code will run on windows machines.
> Because i don't want the users to move the folders around or mess with 
> the program or taking copies home to fiddle with it, i was thinking of a 
> way to check when the program starts that it's still on the same 
> directory and same computer.
> That way i at least avoid unnecessary phone calls asking me for help 
> when they messed the program up.
> I'm thinking of a function that will generate such a code and put it in 
> a file. Then when the program starts it checks this file and checks the 
> code in there with a code that it generates at that time again based for 
> instance on the current directory and other components unique to that 
> computer. It could be a long string (but what info?) and then take a 
> hash from it and store the hash value.
> How could i construct such a code without being a total pain? For 
> instance i don't want to check for anything hardware related because 
> then my program would fail to work once the people change their hardware.
> Anyway, it doesn't need to be waterproof. (not possible anyway)

Your requirements are confusing -- you want the program to check "that 
it's still on the same ... computer" but you don't want it to fail if 
they change their hardware???

In short: don't bother. You will end up annoying people who have not 
"messed with" your software. Heuristics like "it's not on the same 
computer therefore it's been fiddled with" don't seem like a good idea.

An app should not care where it is installed, so long as it can find its 
associated files and folders. If the app can't find them:

Try putting out informative messages when something does go wrong, and 
write a copy to a dump-file (like the Dr Watson log file, but skip all 
the hexdump stuff). Put a timestamp and the computer name and the user's 
name and whatever else you can dig out of Windows in the dump-file. Then 
you can ask the user with a problem to e-mail you a copy of the 
dump-file. If (say) the computer name is "frodo" instead of 
"pathology03" then you can tell the user their usage is not supported. 
This is a good idea even with "normal" i.e. non-fiddling users, who 
can't remember what the error message said -- they've since killed the 
window or even re-booted their PC.

Iy you tend towards paranoia, put a checksum somewhere in each message 
in case the devious fiends use Notepad to change "frodo" to 
"pathology03" :-)

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