What makes this even more ridiculous is by the most literal definition, most of modern cryptography is "security by obscurity." My TLS or SSH connection remain

What makes this even more ridiculous is by the most literal definition, most of modern cryptography is "security by obscurity." My TLS or SSH connection remains secure because my selected private key remains obscure and hard to find in a space of 2^128 possible keys. Only a handful of techniques (quantum key exchange, one-time pads) are not relying on obscurity for their security. Security through obscurity works perfectly well so long as you correctly quantify the size of the search space, the bits of information provided as hints, and the cost of searching--which basically describes what much of modern cryptography is about, at the primitive construction layer. By the same measure, a multi-million dollar cache in the American Rocky Mountains remained unfound for a decade despite there being a poem and short story filled with clues as to its location[1]. If I go totally off-grid for 6 months, and then come out of the wilderness saying that at some point during that wandering I cached my valuable possessions in a secret location, you're not going to find it. The admonition not to use security by obscurity is well-meaning but requires explanation. We shouldn't hide things in ad-hoc search spaces that haven't been adequately formalized. We should prefer mathematical puzzles which have well characterized properties. And generally that is good advice. But that doesn't mean we shouldn't also throw in whatever extra protections are convenient, even if they're ad-hoc or provide insufficient bits of security by themselves. [1] https://en.wikipedia.org/wiki/Fenn_treasure https://en.wikipedia.org/wiki/Fenn_treasure