How does Safedisc 2 work?

[Copytrooper]

SafeDisc1 had defect sectors in the area 800-10000, SafeDisc2 also has the so-called weak sektors -> good sectors with a special bit pattern which will be written bad by most writers ... these sectors are used to decrypt the game .exe, so if these sectors are unreadble on cd-r the game crashes ...
there are some other checks (e.g. ATIP) ...