This is the Verification API (Backend Server)

The purpose of this module is to put the zkSNARK into a proper feasible workflow.

This package too will be published as an npm package. To install this head over to your terminal and type:

$ npm i @0xagnish/zkVerifier

To initialise the library:

import { Prover, UserVerifier } from "0xagnish/zkVerifier";
import { MerkleSumTree } from "0xagnish/zkDataPrep";

Prover here is the core API class that generates the Proof of Solvency zkSNARK for each of the users in the given input.csv. Since, the proof is a Zero-Knowledge Proof, it doesn't provide much information about the internal details about the entries of the database. Entries here refer to as the username -> balance structs of the individual users. Thereby, not revealing the number of users, or any kind of numerical value to the ongoing assets and liabilities of the Company/Organization.

UserVerifier is a class, rather an Abstraction Layer that lets a user verify a proof, without getting into the hassle of how the internals of the zero-knowledge verifier is working.

MerkleSumTree, as explained in 0xagnish/zkDataPrep structures the input.csv data into a merkle sum tree, a data structure that helps in construction of the dataset into a zk-friendly manner.

Usage

new Prover (tree: MerkleSumTree, assetsSum bigInt, proverArtifacts SnarkProverArtifacts) : Prover

import { Prover } from "0xagnish/zkVerifier";
import { MerkleSumTree } from "0xagnish/zkDataPrep";

const tree = new MerkleSumTree(
  "provide the relative path of the input.csv file"
);

const assetsSum = BigInt(4000000000);

const pathToWasm = "..enter your file path for WASM";
const pathToZKey = "..enter your file path to ZKEY";

const proverArtifacts = {
  wasmFilePath: pathToWasm,
  zkeyFilePath: pathToZKey,
};

const prover = new Prover(tree, assetsSum, proverArtifacts);

Initializes the prover object and takes inputs from the Merkle Sum Tree, the total assets owned by the Company/Organization. Along with the zkSNARK artifacts, which mainly consists of the Proof file, Proving Key and Verification Key.

The circuit repository is available in the @0xagnish/zkCircuits npm package, you can install by calling :

$ npm install 0xagnish/zkCircuits

generateProof (user index number : int) : FullProof

Generates a Proof-of-Solvency proof for a specific user in the Merkle Sum Tree.

const userIndex = 0;
const proof = await prover.generateProofForUser(userIndex);

APIs -> UserVerifier

new UserVerifier (username: string, balance: uint, verificationKey: JSON) : UserVerifier

import { UserVerifier } from "0xagnish/zkVerifierServer";

const username = "randome-string";
const balance = BigInt(2204);
const verificationKey = require("...add the file path to the verification key...");

const userVerifier = new UserVerifier(username, balance, verificationKey);