Black Box

A black box is an object that accepts input and generates output without the solvers knowing the rules that govern the operation of the black box. Often, the puzzle involves figuring out how the black box works, then using the rules of the black box to create inputs or outputs with a desired property.

Puzzle Application
Black boxes can be designed for any plausible function; in puzzles, however, they most often act upon a text input. Black box puzzles will often also provide some of their "rules of operation" while keeping the functions themselves secret: some will directly have instructions on what constitutes a valid query, while others will reflect part of their inner workings upon being presented with an input.

Black box puzzles are also almost always interactive puzzles.

There will also almost always be a "goal": determining what a certain input will output (while the black box forbids that input from being used directly) or determining what inputs will generate a certain output. These goals are often tied to extraction.

Strategy
The key to deciphering black boxes is to carefully craft inputs that allow for discerning the rules. What counts as such an input will obviously vary between puzzles; however, consistency in function is generally valued. If the solver can guarantee that a series of input-output relationships follow the same function, that function becomes easier to identify.

Notable Examples

 * Pipe (MIT Mystery Hunt 2015) -
 * Functional Analysis (Teammate Hunt 2020) - Where
 * Nutraumatic (MIT Mystery Hunt 2021) - A black box puzzle taking the guise of the popular Wheel of Fortuning tool Nutrimatic.
 * Sorcery for Dummies (MIT Mystery Hunt 2022) - Where