tornado-nova/src/index.js

const MerkleTree = require('../lib/merkleTree')
const fs = require('fs')
const { bigInt, stringifyBigInts } = require('snarkjs')
const crypto = require('crypto')
const Hasher = require('../lib/mimc')
const Web3 = require('web3')
const buildGroth16 = require('websnark/src/groth16')
const websnarkUtils = require('websnark/src/utils')

let contract, web3, circuit, proving_key, groth16
const hasher = new Hasher()

// console.log(hasher.hashArray(['21663839004416932945382355908790599225266501822907911457504978515578255421292', '21663839004416932945382355908790599225266501822907911457504978515578255421292']))

const MERKLE_TREE_HEIGHT = 5
const RPC_URL = 'http://localhost:8545'

/** Generate random number of specified byte length */
const rbigint = (nbytes = 31) => bigInt.leBuff2int(crypto.randomBytes(nbytes))

/** BigNumber to hex string of specified length */
const toHex = (number, length = 32) => '0x' + (number instanceof Buffer ? number.toString('hex') : bigInt(number).toString(16)).padStart(length * 2, '0')


function merklePathIndicesToBigint(indexArray) {
  let result = 0
  for(let item of indexArray.slice().reverse()) {
      result = (result << 1) + item
  }
  return result
}

function fromPrivkey(privkey) {
  return {
    privkey,
    pubkey: hasher.hashArray([privkey]),
  }
}

function randomKeypair() {
  return fromPrivkey(rbigint())
}

function createZeroUtxo(keypair) {
  return createUtxo(
    0,
    rbigint(),
    keypair.pubkey,
    keypair.privkey,
    Array(MERKLE_TREE_HEIGHT).fill(0),
    Array(MERKLE_TREE_HEIGHT).fill(0)
  )
}

function createOutput(amount, pubkey) {
  if (!pubkey) {
    throw new Error('no pubkey')
  }
  return createUtxo(amount, rbigint(), pubkey)
}

function createInput(amount, blinding, pubkey, privkey, merklePathIndices, merklePathElements) {
  return createUtxo(amount, blinding, pubkey, privkey, merklePathIndices, merklePathElements)
}

/// unsafe function without sanity checks
function createUtxo(amount, blinding, pubkey, privkey, merklePathIndices, merklePathElements) {
  let utxo = { amount, blinding, pubkey, privkey, merklePathIndices, merklePathElements }
  utxo.commitment = hasher.hashArray([amount, blinding, pubkey])
  if (privkey) {
    utxo.nullifier = hasher.hashArray([utxo.commitment, merklePathIndicesToBigint(merklePathIndices), privkey])
  }
  return utxo
}

function createDeposit(amount, pubkey) {
  const keypair = randomKeypair()
  const tx = {
    inputs: [createZeroUtxo(keypair), createZeroUtxo(keypair)],
    outputs: [createOutput(amount, pubkey), createZeroUtxo(keypair)], // todo shuffle
  }
  return tx
}

async function buildMerkleTree() {
  console.log('Getting contract state...')
  const events = await contract.getPastEvents('NewCommitment', { fromBlock: 0, toBlock: 'latest' })
  const leaves = events
    .sort((a, b) => a.returnValues.index - b.returnValues.index) // todo sort by event date
    .map(e => e.returnValues.commitment)
  return new MerkleTree(MERKLE_TREE_HEIGHT, leaves)
}

async function insertOutput(tree, output) {
  await tree.insert(output.commitment)
  let { path_elements, path_index } = await tree.path(tree.totalElements - 1)
  output.merklePathIndices = path_index
  output.merklePathElements = path_elements
}

async function deposit() {
  const amount = 1e6
  const tree = await buildMerkleTree()
  const oldRoot = await tree.root()
  const keypair = randomKeypair()
  const tx = createDeposit(amount, keypair.pubkey)
  await insertOutput(tree, tx.outputs[0])
  await insertOutput(tree, tx.outputs[1])
  console.log('Note', tx.outputs[0])

  let input = {
    root: oldRoot,
    newRoot: await tree.root(),
    inputNullifier: [tx.inputs[0].nullifier, tx.inputs[1].nullifier],
    outputCommitment: [tx.outputs[0].commitment, tx.outputs[1].commitment],
    extAmount: amount,
    fee: 0,
    recipient: 0,
    relayer: 0,

    // private inputs
    privateKey: tx.inputs[0].privkey,

    // data for 2 transaction inputs
    inAmount: [tx.inputs[0].amount, tx.inputs[1].amount],
    inBlinding: [tx.inputs[0].blinding, tx.inputs[1].blinding],
    inPathIndices: [merklePathIndicesToBigint(tx.inputs[0].merklePathIndices), merklePathIndicesToBigint(tx.inputs[1].merklePathIndices)],
    inPathElements: [tx.inputs[0].merklePathElements, tx.inputs[1].merklePathElements],

    // data for 2 transaction outputs
    outAmount: [tx.outputs[0].amount, tx.outputs[1].amount],
    outBlinding: [tx.outputs[0].blinding, tx.outputs[1].blinding],
    outPubkey: [tx.outputs[0].pubkey, tx.outputs[1].pubkey],
    outPathIndices: merklePathIndicesToBigint(tx.outputs[0].merklePathIndices.slice(1)),
    outPathElements: tx.outputs[0].merklePathElements.slice(1)
  }

  console.log('input', JSON.stringify(stringifyBigInts(input)))

  console.log('Generating SNARK proof...')
  const proofData = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key)
  const { proof } = websnarkUtils.toSolidityInput(proofData)

  const args = [
    toHex(input.root),
    toHex(input.newRoot),
    [toHex(tx.inputs[0].nullifier), toHex(tx.inputs[1].nullifier)],
    [toHex(tx.outputs[0].commitment), toHex(tx.outputs[1].commitment)],
    toHex(amount),
    toHex(input.fee),
    toHex(input.recipient, 20),
    toHex(input.relayer, 20),
  ]

  console.log('Sending deposit transaction...')
  const receipt = await contract.methods.transaction(proof, ...args).send({ value: amount, from: web3.eth.defaultAccount, gas: 1e6 })
  console.log(`Receipt ${receipt.transactionHash}`)
}

async function transact() {

}

async function main() {
  web3 = new Web3(new Web3.providers.HttpProvider(RPC_URL, { timeout: 5 * 60 * 1000 }), null, { transactionConfirmationBlocks: 1 })
  circuit = require('../build/circuits/transaction.json')
  proving_key = fs.readFileSync('../build/circuits/transaction_proving_key.bin').buffer
  groth16 = await buildGroth16()
  netId = await web3.eth.net.getId()
  const contractData = require('../build/contracts/TornadoPool.json')
  contract = new web3.eth.Contract(contractData.abi, contractData.networks[netId].address)
  web3.eth.defaultAccount = (await web3.eth.getAccounts())[0]

  await deposit()

}

main()