I'm wondering –considering GRCon'21 has another Capture The Flag challenge– whether such signal-centric problems, which typically also involve a more "classical" infosec problems but do need contestants to apply their investigative mind to signal processing / SIGINT problems are subject of this SE site, too.

AFAIK CtF questions are basically only admissible if the asker doesn't ask us to solve the flag for them, and I don't know where exactly you'd want to draw the line on advising people that might have more of a signal processing background on infosec approaches.

1 Answer 1


If it is legitimately about security and the specific CTF challenge instance isn't an arbitrary technology "just to be challenging", then I don't see why not.

  • That's the thing, though: The contestants aren't mainly breaking security of a system; that might be part of the things they do. But the weight of the flags usually is (and I say "usually", because I'm actively not involved in the flag-generation) is gathering information from signals that don't give that away easily. It is information security in the literal sense of the word. It's only partially about computer systems, i.e. only partially about information security in the narrower sense. Commented Sep 16, 2021 at 19:46
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    The site covers more than digital security. We cover information on paper and we've entertained several physical security questions. So, just being non-digital isn't a problem. However, if the question becomes solely about this CTF and has no applicability to security outside of this CTF, then it becomes "too localised" (an old close reason).
    – schroeder Mod
    Commented Sep 16, 2021 at 20:10
  • yeah, I think that's more than fair. Thanks! Commented Sep 16, 2021 at 20:10

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