I can try to locate the articles I've read on this, as they should be available on-line. But am not prepared to do this right now (tired).

But you may have heard of this, anyway. With the experiments in quantum teleportation of photons a success, the military started looking for applications for this new cool tool.

Turns out quantum teleportation of photons allows the two parties involved, sender and receiver, to possess a key that is completely unbreakable.

As we move further into the Information Age, I can only think it will be natural for us to employ more codes to secure our information in a world of disappearing privacy and increasing threats to secrecy and security. Would other civilizations, organized as societies, do otherwise? Perhaps. My guess, however, is that division of labor, prioritization of tasks and resources, etc., will ensure that they will be enough like us to be recognizable as societies. Not just societies, but technological societies. Primitives don't build spaceships or SETI beacons or comsats.

So coded transmissions are to be expected. Throw on top of that a culture and communication system ('language') completely unrelated to our own. No way will we be decoding any alien transmissions.

Unless they are transmissions intentionally aimed at us for the purpose of communication. I deem this unlikely, but there is the slim possibility it could happen.

As technological species build better and better equipment that wastes less energy and less signal, there'll also be less for us to detect. And, as I mentioned in my other post on this thread, the effect of scintillation on signals traveling through interstellar space should take care of the rest.

The odds are way, way against any ET signal ever reaching us in recognizable condition. Or reaching us at all.