5

They used a scrambler[wikipedia] (not “encryption“ and definitely not a “One-Time-Pad” as some think [comment] [comment]) to transmit messages via a SatCom (read: military satellite) system. The scrambler they used back then was (let's just call it) “non-optimal” and has been replaced with an enhanced system. That's also what the sign is hinting at, among ...


2

The online magma calculator http://magma.maths.usyd.edu.au/calc/ tells me this LFSR corresponds to a primitive polynomial since $$G(X) = X^{23} + X^ {21} + X^{16} + X^{8} + X^5 + X^2 + 1$$ is primitive. Thus, some phase of the output sequence is given by $$tr(\alpha^t)$$ where $tr:GF(2^{23})\rightarrow GF(2)$ is the trace map and $\alpha \in GF(2^{23})$ ...


Only top voted, non community-wiki answers of a minimum length are eligible