There is a max comment depth for me for some reason so I cannot reply to graypegg directly... ZK-proofs are more advanced than just cryptographic signatures. T

There is a max comment depth for me for some reason so I cannot reply to graypegg directly... ZK-proofs are more advanced than just cryptographic signatures. The important point is being able to prove something without revealing the proof itself. Classic example is proving that you have a solution to a sudoku board without revealing the solution. Most ZK proofs actually rely on proving something with some probability. That means I don't prove to you with 100% certainty that I know the sudoku solution, but rather the chance of me lying about knowing a solution is < 0.00000001%. Traditionally, zk proofs required many iterations to justify the probability of the proof. Blockchain use cases advanced research in "succinct" proofs. If you search for ZKSNARK, ZKPLONK, and ZKSTARK you will find some examples. To compare to a cryptographic signature, I can use classic cryptography to prove that I know a value by sharing a signed hash of that value. However, you can only verify my proof when I reveal the pre-image. Doing the proof entirely on encrypted data is homomorphic encryption, and modern zk proofs make use of homomorphic encryption to prove things about arbitrary computation.