> All modes of cyber security depend on some obscurity (e.g. password)

That's not what the expression means.

"Security through obscurity" has a very specific meaning — that your system's security depends on your adversary not understanding how it works. E.g. understanding RSA is a few wikipedia articles away, and that doesn't compromise its security, so RSA isn't security through obscurity.

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sroussey 2 hours ago | parent | next [-]

No, "Security through obscurity" is a valid and useful layer. A lot of weight hangs on your word “depends” though, in which case if it is the only layer then you will eventually have, uh, problems.

I’ve used it for a long long time. Like in 1999 I’d have a knock on certain ports in a certain order to unlock the ssh port.

And lots of weird stuff to stop forum spam. Which could work for weeks or months or even a year.

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pdpi an hour ago | parent [-]

Port knocking isn't security through obscurity. Given the knowledge that you have a port knocking system in place doesn't tell me what specific sequence of knocks will open up the service I want to target. Even just a two knock sequence gives you a key with 32 bits of entropy, which makes it trivial to block attempts at bruteforcing the key.

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ZoomZoomZoom 35 minutes ago | parent [-]

I don't see how your argument makes sense. It's all just bits of entropy in the end, be it knowing a port to connect to or a character in your key.

	▲	pdpi 13 minutes ago \| parent [-]
		Yeah absolutely. That was precisely my point — Requiring a secret (be it a password or the private part of an asymmetric key) isn't security through obscurity, and finding the sequence of knocks is equivalent to finding a password of equivalent complexity.

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strken 2 hours ago | parent | prev [-]

Lucketone likely knows this and was pointing out that "obscurity" is a misleading word to use when talking about systems which all rely on obscurity, in the plain English sense of the word.

	▲	pdpi an hour ago \| parent [-]
		We're in a technical forum, discussing a term of art that refers to a very specific bad practice. Lucketone's argument is essentially saying that the bad practice itself isn't actually a bad practice by equivocating the term of art and the plain language definition.