Customer credit card data held by Sony as part of its PlayStation Network (PSN) and Qriocity services was fully encrypted. Sony has refused to rule out that the data could still have been compromised, a veiled reference perhaps to the remote possibility that hackers also accessed the keys used to scramble the data. To use the cards attackers would also, in theory, need to obtain the three-digit card verification numbers, which are not stored by payment systems, although this system is far from foolproof.”]