tornado-core/cli.js

#!/usr/bin/env node
const fs = require('fs');
const assert = require('assert');
const snarkjs = require("snarkjs");
const bigInt = snarkjs.bigInt;
const utils = require("./scripts/utils");
const merkleTree = require('./lib/MerkleTree');
const Web3 = require('web3');
const buildGroth16 = require('websnark/src/groth16');
const websnarkUtils = require('websnark/src/utils');

let web3, mixer, circuit, proving_key, groth16;
let MERKLE_TREE_HEIGHT, AMOUNT, EMPTY_ELEMENT;
const inBrowser = (typeof window !== "undefined");

function createDeposit(nullifier, secret) {
  let deposit = {nullifier, secret};
  deposit.preimage = Buffer.concat([deposit.nullifier.leInt2Buff(32), deposit.secret.leInt2Buff(32)]);
  deposit.commitment = utils.pedersenHash(deposit.preimage);
  return deposit;
}

async function deposit() {
  const deposit = createDeposit(utils.rbigint(31), utils.rbigint(31));

  console.log("Submitting deposit transaction");
  await mixer.methods.deposit("0x" + deposit.commitment.toString(16)).send({ value: AMOUNT, from: (await web3.eth.getAccounts())[0], gas:1e6 });

  const note = "0x" + deposit.preimage.toString('hex');
  console.log("Your note:", note);
  return note;
}

async function withdraw(note, receiver) {
  let buf = Buffer.from(note.slice(2), "hex");
  let deposit = createDeposit(bigInt.leBuff2int(buf.slice(0, 32)), bigInt.leBuff2int(buf.slice(32, 64)));

  console.log("Getting current state from mixer contract");
  const events = await mixer.getPastEvents('LeafAdded', {fromBlock: mixer.deployedBlock, toBlock: 'latest'});
  const leaves = events.sort(e => e.returnValues.leaf_index).map(e => e.returnValues.leaf);
  const tree = new merkleTree(MERKLE_TREE_HEIGHT, EMPTY_ELEMENT, leaves);
  const validRoot = await mixer.methods.isKnownRoot(await tree.root()).call();
  // todo make sure that function input is 32 bytes long
  const isSpent = await mixer.methods.isSpent("0x" + deposit.nullifier.toString(16)).call();
  assert(validRoot === true);
  assert(isSpent === false);

  const leafIndex = leaves.map(el => el.toString()).indexOf(deposit.commitment.toString());
  assert(leafIndex >= 0);
  const {root, path_elements, path_index} = await tree.path(leafIndex);
  // Circuit input
  const input = {
    // public
    root: root,
    nullifier: deposit.nullifier,
    receiver: bigInt(receiver),
    fee: bigInt(0),

    // private
    secret: deposit.secret,
    pathElements: path_elements,
    pathIndex: path_index,
  };

  console.log("Generating SNARK proof");
  const proof = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key);
  const { pi_a, pi_b, pi_c, publicSignals } = websnarkUtils.toSolidityInput(proof);

  console.log("Submitting withdraw transaction");
  await mixer.methods.withdraw(pi_a, pi_b, pi_c, publicSignals).send({ from: (await web3.eth.getAccounts())[0], gas: 1e6 });
  console.log("Done");
}

async function init() {
  let contractJson;
  if (inBrowser) {
    web3 = new Web3(window.web3.currentProvider, null, {transactionConfirmationBlocks: 1});
    contractJson = await (await fetch('build/contracts/Mixer.json')).json();
    circuit = await (await fetch('build/circuits/withdraw.json')).json();
    proving_key = await (await fetch('build/circuits/withdraw_proving_key.bin')).arrayBuffer();
    MERKLE_TREE_HEIGHT = 16;
    AMOUNT = 1e18;
    EMPTY_ELEMENT = 0;
  } else {
    web3 = new Web3('http://localhost:8545', null, {transactionConfirmationBlocks: 1});
    contractJson = require('./build/contracts/Mixer.json');
    circuit = require("./build/circuits/withdraw.json");
    proving_key = fs.readFileSync("build/circuits/withdraw_proving_key.bin").buffer;
    require('dotenv').config();
    MERKLE_TREE_HEIGHT = process.env.MERKLE_TREE_HEIGHT;
    AMOUNT = process.env.AMOUNT;
    EMPTY_ELEMENT = process.env.EMPTY_ELEMENT;
  }
  groth16 = await buildGroth16();
  let netId = await web3.eth.net.getId();
  const tx = await web3.eth.getTransaction(contractJson.networks[netId].transactionHash);
  mixer = new web3.eth.Contract(contractJson.abi, contractJson.networks[netId].address);
  mixer.deployedBlock = tx.blockNumber;
  console.log("Loaded");
}

// ========== CLI related stuff below ==============

function printHelp(code = 0) {
  console.log(`Usage:
  Submit a deposit from default eth account and return the resulting note 
  $ ./cli.js deposit
  
  Withdraw a note to 'receiver' account
  $ ./cli.js withdraw <note> <receiver>
  
Example:
  $ ./cli.js deposit
  ...
  Your note: 0x1941fa999e2b4bfeec3ce53c2440c3bc991b1b84c9bb650ea19f8331baf621001e696487e2a2ee54541fa12f49498d71e24d00b1731a8ccd4f5f5126f3d9f400
  
  $ ./cli.js withdraw 0x1941fa999e2b4bfeec3ce53c2440c3bc991b1b84c9bb650ea19f8331baf621001e696487e2a2ee54541fa12f49498d71e24d00b1731a8ccd4f5f5126f3d9f400 0xee6249BA80596A4890D1BD84dbf5E4322eA4E7f0
`);
  process.exit(code);
}

if (inBrowser) {
  window.deposit = deposit;
  window.withdraw = async () => {
    const note = prompt("Enter the note to withdraw");
    const receiver = (await web3.eth.getAccounts())[0];
    await withdraw(note, receiver);
  };
  init();
} else {
  const args = process.argv.slice(2);
  if (args.length === 0) {
    printHelp();
  } else {
    switch (args[0]) {
      case 'deposit':
        if (args.length === 1) {
          init().then(async () => deposit()).then(() => process.exit(0)).catch(err => {console.log(err); process.exit(1)});
        }
      else
        printHelp(1);
        break;

      case 'withdraw':
        if (args.length === 3 && /^0x[0-9a-fA-F]{128}$/.test(args[1]) && /^0x[0-9a-fA-F]{40}$/.test(args[2])) {
          init().then(async () => withdraw(args[1], args[2])).then(() => process.exit(0)).catch(err => {console.log(err); process.exit(1)});
        }
      else
        printHelp(1);
        break;

      default:
        printHelp(1);
    }
  }
}