PS2 Savegame folder/file name algorithm?

[FrankTHPS]

Hi all,

I'm new to programming and I'm trying to make a PHP script to convert THPS PC to PS2 save games and vice versa (just for fun and exercise purposes).
I found out that the last 8 (alphabetic lowercase) characters of the names of the ps2 save folder/files are associated to the names of how they were saved in the game itself (so they're not just random).

For example:
A THUG2 NTSC save folder/file name always starts with 'BASLUS-20965' and ends with 8 characters like I mentioned before.
A game saved as "Custom Skater" will be always be "BASLUS-20965tbtpgjga".
So "Custom Skater" is being converted to "tbtpgjga".

Does anyone know which algorithm is used for these last 8 characters, or how to find out?
And is there any WAD extractor for Mac? This way I would be able to look into the files if I can find more info about this myself.

[Catarax]

Emulate Windows for the tools here.