...[I]t has a very large problem: if any [forty] devices conspire, they can break the security of the system.Link
To see how, let’s do an example. Suppose that Alice, Bob, Charlie, and Diane conspire, and that the conspiracy wants to figure out the secret vector of some innocent victim, Ed. Ed’s addition rule is “+”, and his secret vector is, of course, a secret.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.