Can I Reveal Part of My Answer To You, Without Revealing The Rest of It? … Meet Accumulators and Witnesses
Let’s say a teacher asks pupils to name six of the largest counties in the world. The answers would be: Canada, Russia, China, US, Brazil and Australia. Now she tells the pupils to not show their answers but to commit them onto a piece of paper. After this, the teacher asks each pupil to show evidence of the counties they have selected with something she could witness, but not reveal the answer. She calls out Russia, and ask pupils to reveal their evidence, but not their answer. The pupils hold up the evidence and the teacher checks it. This evidence might be a drawing of the Russian flag, and the teacher can then witness the answer, without the pupil revealing the answer they have given. This is the wonderful world of zero-knowledge proofs and where we can commit to data, and then reveal part of it when required, without revealing the rest of the data we have.
Accumulators — adding and removing data
An accumulator allows Bob to add values onto a fixed-length digest, and to provide proof of the values added, without revealing them within the accumulated value. In this case, we will add a number of strings “alice”, “bob” “eve”, “carol”, “dave”, “grace” and “faith”. Bob can then provide witness proof that one of…
