Treyarch actually bothered protecting the gamesave on WaW
And btw, its NOT encrypted
Its hashed

Only the game disc can read or write to the save file
And everytime the game is saved, the algorithm for saving is altered and changed
So basically, everyones game saves are different, similar, but different
Every one is unique, nothing is impossible, but its very hard to work around
Lazy game developers (Infinity Ward, EA, etc...) just leave their game saves unprotected
Treyarch actually care about the PS3 platform, unlike the aforementioned game developers