Watched a talk about a parabolic link that was supposed to provide secure point to point communication over long distances (think direct communication between two office buildings), it was either stated or heavily implied that the data was encrypted i don’t remember

They did some testing and found that it used some standard frequency and protocol to send it, and it was just sending the ethernet frames as-is except with one change, they padded it with a single zero bit in the beginning and 7 at the end…

Once you knew this it was reasonably trivial to read everything going through the link, or to inject your own packets

Never trust companies to do security right