Radio noise at most locations is mostly man-made (thermal noise from the circuitry and QRM from external sources). At some frequencies, QRN from the sun / ionospheric interactions might be more significant, but overall it's mostly man-made. Well down here on Earth at least.
You can definitely construct better receivers with lower NF and by that logic they simply decrypt the noise so that you can receive the weak signal that is otherwise drown in noise.
As per the galactic radio noise, CMB and distant strong radio sources - they are very very weak as compared to man-made noise (that's why they build huge radiotelescopes with very high gain).
TLDR; what you think is random radio noise is mostly generated by us. Theoretically with enough data and compute resources it could be modeled precisely and then "decrypted"
I wanted, when i was younger, to write a story where someone learned about Issac Asimov's Psychohistory and realized that they could do the same thing with like... gravity (or something, i didn't work out the techno babble)
Then read Hitch Hikers guide, and read about the Total Perspective Vortex
Plug Machina into Deus, and you have a little machine that can tell you anything that ever happened anywhere in the universe by analyzing but it can't predict the future because it can only see effects.
Say it again for the people in the back, 🙌 @swiftonsecurity "The difference between encrypted information and radio noise is your faith there cannot be a key for the static."
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Then read Hitch Hikers guide, and read about the Total Perspective Vortex
https://en.m.wikipedia.org/wiki/Permutation_City