“Eddie’s theory is that, once a civilization is advanced, it encrypts everything, so that eavesdroppers from afar, if they see anything at all, see only white noise, not signs of civilization.”
The alleged Snowden claim is nonsensical.
1. If the “advanced” civilization is attempting to communicate with previously unknown civilizations using radio energy, the radio frequencies to be used are rather obvious due to the limitations of using other radio frequencies, and encryption of the radio communications would be obviously contrary to the purpose of making First Contact using such primitive technology.
2. Using encryption with radio transmissions is far too slow and too weak in power across interstellar and intergalactic distances to be useful for most any communications other than First Contact, which requires the communications to not be encrypted.
3. Humans cannot “eavesdrop” on the radio emissions of alien civilizations, because those radio emissions are too weak in power to be detectable at the Earth, with the only exception of extremely high power (many terawatts) narrow band transmissions designed for non-encrypted First Contact purposes within about one thousand light years (LY) of the Earth. The radio emissions and radio frequency interference emissions of alien civilizations would be undetectable beyond a distance of a fraction of a single light year from the sources due to the dissipation of the radio energy and interstellar plasma.
The whole premise of the alleged Snowden claim appears to be another hoax.
1. If the “advanced” civilization is attempting to communicate with previously unknown civilizations using radio energy, the radio frequencies to be used are rather obvious due to the limitations of using other radio frequencies, and encryption of the radio communications would be obviously contrary to the purpose of making First Contact using such primitive technology.
Snowden's talking about routine communications being intercepted by distant civilizations, not about deliberate attempts by one civilization to contact others which may be somewhere "out there". His argument is that such ordinary traffic, if receivable at all, would be indistinguishable from noise, due to routine encryption employed by civilizations advanced beyond a certain level.
SETI is also a monumental waste of time and effort, for many reasons already discussed on this thread.
Think of the analogy of an ant walking on top of a newspaper.
The word they are walking on is “Chicago”.
They don’t know what the language is. They don’t know what it describes. Even if they knew it was a place they wouldn’t know how to get there. Even if they got there it wouldn’t make sense why it was there or what is was.
Alien means alien.
Only dumb ants believe otherwise.