C-Deck was a communications deck on the Providence-class carrier/destroyer of the Super tactical droid Aut-O, where the Separatist encryption module was kept. Around 20 BBY, the C-Deck was hacked into by the D-Squad, an elite group of droids put together for this specific task. C-Deck contained a vault with an encryption module that was stolen by the D-Squad to decipher a Confederate transmission sent out by General Grievous.