Step one: send a file that's cryptographically signed.
Step two: the client solves the problem of "which of these duplicate and conflicting packets do I need to assemble together to make a message that is appropriately signed?"
Some customers (e.g. DOD) sent in clear, unsigned. They trusted their networks.
Wow. I had no idea. This may be one of the dumbest things I've ever read. Encryption is free.
A brilliant woman from, where, Slovenia? figured a way to use SSE instructions to encrypt just as fast as the built-in instructions, I think 2 cycles per byte.
I guess DJB's ciphers run much the same way, nowadays.
There are pretty good references starting from https://crypto.stanford.edu/vpaes/ .
So they started using Aspera to send video from the UAVs over Iraq etc. to the Pentagon. Before that, they were literally flying boxes of videotapes (or CDs? Tapes seem hard to believe, except this was govt.) to a warehouse, where analysts could check them out, like from your neighborhood library.
Probably now it's all realtime. But they have to stream it, somehow, so it is likely still going via Aspera to Nevada or wherever they work the remote pilots.
On first read I thought you meant Aspera ran on the UAVs :) but I now realize the high unlikeliness of that...
Jihadists could tune in an ordinary scanner, and watch the video coming from them. Embarrassing.