[extropy-chat] Covert channels (was Re: Transhumanist short story)

[David Lubkin]

scerir wrote:

>We quantify information in terms of how much stuff you need to tell/send 
>me before I get to know something. But can I get to know something without 
>you telling/sending me anything [1], or almost anything [2], or something 
>random [3]?

This reminds me of the concept of communicating through a covert channel. I 
think I first heard about it in a mandatory security lecture at Livermore 
during the Cold War. It struck me that there are so many ways to signal 
that clever operatives can effectively guarantee that they avoid detection, 
as long as they keep the data rate low enough.

"If Natasha posts to exi-chat on the Monday of a three-day weekend, that's 
a 1 signal to Boris; if she doesn't, that's a 0."

"If Boris posts a picture to alt.binaries.pictures.smurf, the signal is bit 
117."

With rules that obscure but that precise, one could imagine software that 
automatically spread the message across 1000 channels, each of which used a 
different rule to transmit one bit. Letting you jack up the data rate 
without substantially increasing the risk of detection or decryption.

The next step would be to generate 10^6 or 10^9 algorithms, each of which 
is used once to transmit one bit. A one-time pad of covert channels.


-- David Lubkin.