> For Sudoku, that's easy to verify. I meant: For Sudoku, it's s easy to verify that a given solution is correct. (cannot edit) Of course, being given the sol

> For Sudoku, that's easy to verify. I meant: For Sudoku, it's s easy to verify that a given solution is correct. (cannot edit) Of course, being given the solution first in order to even try, can be a bit boring. For that, there exists "zero-knowledge proof" where one can reveal one knows an answer, without actually divulging it. Here is a writeup about someone doing that for Sudoku: https://manishearth.github.io/blog/2016/08/10/interactive-sudoku-zero-knowledge-proof/ https://manishearth.github.io/blog/2016/08/10/interactive-su...