I believe when you sign in at the door they don't give you any identifier, just a wristband identical to everyone else's. They are trying to prevent ticket scalping, however.
I don't expect them to give any data to anyone besides the payment processor, and knowing the CCC, their own system is probably either self-hosted or at a European cloud vendor. Bank transfer is a payment option, so you don't have to use an American card network - when you use a European bank transfer, no data goes to America on purpose (they are presumably still wiretapping it).
When I was at CCCamp, there was a power outage that included the network hub, and the network was down for an additional half hour while they tried to find the person with the disk encryption password of the DHCP server.
I don't expect them to give any data to anyone besides the payment processor, and knowing the CCC, their own system is probably either self-hosted or at a European cloud vendor. Bank transfer is a payment option, so you don't have to use an American card network - when you use a European bank transfer, no data goes to America on purpose (they are presumably still wiretapping it).
When I was at CCCamp, there was a power outage that included the network hub, and the network was down for an additional half hour while they tried to find the person with the disk encryption password of the DHCP server.