Signaling/Discrete Communication

Some poker buddies and I recently thought we saw a few people at one of our tables attempting to signal to each other, which is a whole different story in itself, but it got me thinking about communication.

We have all this great communication technology which allows us to talk to each other in an encrypted way, but one of the security flaws is that other people still know with whom and at what time we are communicating. Sometimes even knowing who one is talking with is enough to discern an idea about the conversation, even if the actual message is still obscured.

(For example, if a terror suspect randomly called a suspected terrorist weapons dealer, that's reasonable evidence against both of them, even if the conversation is encrypted. Also, as another example, somebody theorized that Satoshi was either from Western Europe or the Eastern USA based on the times of his posts. So even if the communication is obscured, there is still information leakage based on many other factors.)

So I'm wondering if there's been any developments in the idea of obscuring the mere fact that you are communicating. I can't off the top of my head see specific uses for this or what application of it would look like, but it seems intuitively like it should be a useful idea.

Off the top of my head, I feel like implementation of it would require a ton of data continuously streaming so that any communication is mixed in with white noise, or maybe piggybacking some kind communication on top of normal protocols. But then, how do you alert somebody who doesn't know to be receiving without broadcasting the fact that you wish to talk to them to everybody?

Is this a dumb idea? Are there uses for it? What would it look like in practice?

This was just rumbling around in my head after our poker session and it FELT important, so I wanted to make sure I posted it and asked around before I just dropped it and forgot about it.