Understanding Zero-knowledge proofs through illustrated examples

Completeness - everything that is true has a proof: As long as Alice finds Waldo, she's able to consistently use her proofs to show Waldo, in each game. Put simply, Alice's proof systems convince Bob that she found Waldo. Zero-Knowledge - only the statement being proven is revealed: As Alice proves to Bob that she has found Waldo, the only information revealed to Bob is that "Alice has found Waldo". Put simply, Alice's proof systems prove her victory to Bob, without revealing her knowledge. The following is an example of a non-interactive zero-knowledge proof, which doesn't require the former challenge-response dynamic between Alice and Bob. Such non-interactive proofs let many parties verify Alice's claims, not just Bob.The conundrumAlice wants to prove to Bob and his snooty Sudoku club that she has solved a Sudoku puzzle they have not been able to solve. Alice builds a tamper-proof machine that executes the proof to Bob and friends.