But it still doesn't say 2 - it says "a series". The example afterwards describes one core being reset while another carries on the comms, but the series implies that there would be more cores available to maintain a quorum.
Wouldn't cost much to put a dozen simple cores onto a decent FPGA - not compared to the budgets involved in building, launching and operating a satellite.
I did wonder what they'd be wanting encryption for, because (like OP) my first thought was that the comms is generally a ground->ground relay so the decryption need only happen at the ends. ISS can have the big expensive box because it's a big expensive thing. But then you start considering things like manoeuvring commands, and encryption becomes a real nice-to-have. Besides that there's always a bunch of spooks want their illicit photos from orbit to remain secret.
Biting the hand that feeds IT
