There’s gotta be some kind of existing program that can take your known inputs and outputs and make a guess at generating your universal decoder. A neural net would do it, given enough examples, but perhaps there is a simpler way. Like, sort of a generic key generator or something like that. I’ll bet such a thing exists somewhere.

I mean, also would be fun to figure out by hand, but if the author of the original black box was deliberately trying to obfuscate, that might be tough.

How easy is it to machine-generate a bunch of calls and responses out of the black box? Given enough speed and storage, you wouldn’t need to know the algorithm, just store every possible response in a database.