The only real security there is plain old common sense. When you can't encrypt, fool 'em:
Kirk: Kirk to Enterprise.
Spock: Spock here.
Kirk: Captain Spock, damage report.
Spock: Admiral, if we go "by the book". like Lieutenant Saavik, hours could seem like days.
Kirk: I read you captain. Let's have it.
Spock: The situation is grave, Admiral. We won't have main power for six "days". Auxiliary power has temporarily failed. Restoration may be possible, in two "days". By the book, Admiral.
Reminds me of a scene from "Hot Shots - Part Duex": "Recon reports Indians on the warpath in your area. Over." "Ain't no Indians around here. Over." "Do not take literally. Repeat. Do not take literally." "The vultures are circling the carcass. Repeat. The vultures are circling the carcass. Over." "I see a couple of gulls, but I don't..." "The pit bull is out of the cage. The crips are raiding the store." "Hey, you yanking my crank?"
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