Zero Knowledge Proofs

A good explanation of Zero Knowledge Proofs, starting with simple examples.  Examples of usage at the link. At the tag below there is also a Python implementation example.

Zero-knowledge proof
From Wikipedia, the free encyclopedia

In cryptography, a zero-knowledge proof or zero-knowledge protocol is a method by which one party (the prover) can prove to another party (the verifier) that they know a value x, without conveying any information apart from the fact that they know the value x. The essence of zero-knowledge proofs is that it is trivial to prove that one possesses knowledge of certain information by simply revealing it; the challenge is to prove such possession without revealing the information itself or any additional information.[1]  .... "