Was also used in N. America. It had many vulnerabilities in every card generation. You could program OEM cards, have man-in-the-middle devices, and full emulators.

You Never needed to actually use the cards for Nagra. But The competitor DTV system built by NDS had an ASIC on the chip, so all solutions required a card at some level. But some setups could use one slave card for multiple receivers. Even over IP.

Fun times!