Kerckhoff’s Doctrine
Associated with algorithm is key. All security is in key.
Kerckhoffs: If the strength of your cryptosystem relies on the fact that the attacker does not know the algorithm’s hidden workings, you’re sunk!!!
Key question: can we do it?
As Edgar Allan Poe wrote in “The Gold-Bug”:
It may well be doubted whether human ingenuity can
construct an enigma of the kind which human ingenuity
may not, by proper application, resolve.