|Since the end of 1998 Sony introduced the first protected PlayStation games in Japan (PoPoRogue). They added extra code, called LibCrypt, could detect if a Mod-Chip was being used. When it detected it then game could not be played.
About 6 months later the LibCrypt protection was also used on European PAL games (Medievil) and now also US games are being protected.
The LibCrypt protection uses a Digital ID (16 bit key), which is stored in the SubChannel of a CD-ROM. Until now there have been 4 different protection schemes: LC1, LC2, LC3 & LC4