README.md

zkp-integer-threshold

There are Snarks and other way to build other ZKP consructs.

This is an example using a ZKP integer treshold hashchain as the one described in the VEX paper: https://cs.nyu.edu/~mwalfish/papers/vex-sigcomm13.pdf even if we're applying in this example repository for purposes like "age verification" (prove that a user is over a certain age), or "credit line(s) value in thousandUSDs" or other similar ones.

Install

npm i

Run

npm start

or:

node zkp-hash-range-example.js

Implementation

This is the core implementation of the proofs:

const { createHash, randomBytes } = require('crypto')
const { sha256Hash, hashTimes } = require('./lib/utils')

const genSecret = () => ( randomBytes(32) )

const encryptIntegerThreshold = (intThreshold, secret) => (
  hashTimes(intThreshold+1, secret, sha256Hash)
)

const genIntegerProof = (intThreshold, secretInt, secret) => {
  const integerDifference = intThreshold - secretInt + 1
  return hashTimes(integerDifference, secret, sha256Hash)
}

const verifyIntegerProof = (proof, threshold) => (
  hashTimes(threshold, proof, sha256Hash)
)

In this example, the KYC/Identity provider encryps the shared secret (secret) by hashing it intThreshold + 1 times (encryptedInt = encryptIntegerThreshold(...)). The User prepares a proof that hashes the secret value secretInt, intThreshold - secretInt + 1 times. The verifier will then use the verification function to create a verification output to be compared against the encryptedInt one.

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Contact the developers by opening an issue on the GitHub Repo

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