mhhh sounds interesting this thread here...i would do it a bit different =)
How about something like that:
You create for the file an additional check like with a salt key.
Could looks like: SALT+MD5+Base64..
SALT= Date of modification
those in DES encrypted and both again in base64 =)
Additional to go against some kids you could compile the prototype.py in some dll and this one you just load at the prototype.py =)
Then every 20 sec. just let the client check the base64 key...if it changed somehow (and it's hard for non-padmak's to pump they own files to generate 1:1 the same key) then just kill the process of there binary