[wucke13]

For a local databus it has been relatively unimportant. However, there are radio data links in/out of the aircraft. The scope of data for these links is quite limited today, but likely to grow significantly in the future. There cryptographic properties become important, and a currently missing. An example would be ACARS.

Also in some aircraft types these data buses are unfortunately not so very hard to access (i.e. accessible from the cabin, with undetected access being even plausible in some cases). So some resilience might not hurt in these cases.

It's important that failure of critical systems is far less threatening than systems providing plausible, yet incorrect data. Redundancy and monitoring catches most of the former but not the latter.