multisign_payment.js

var ripple = require('ripple-lib').RippleAPI
var kp = require('ripple-keypairs')

const api = new ripple.RippleAPI({
  server: 'wss://s.altnet.rippletest.net'
});

async function addSigners (account, secret, signers, threshold) {

  let weights = []

  for (let signer of signers) {
    weights.push({
      address: signer.address,
      weight: 1
    })
  }

  const tx = await api.prepareSettings(account, {
    signers: {
      threshold: threshold,
      weights: weights
    }
  })

  const signed = api.sign(tx.txJSON, secret);
  console.log(signed.id)
  return await api.submit(signed.signedTransaction)
}

async function sendPayment (account, destination, signers, threshold) {
  let signatures = []

  for (let i=0; i<threshold; i++) {
    const tx = await api.preparePayment(account,
      {
        "source": {
          "address": account,
          "amount": {
            "value": "1",
            "currency": "XRP"
          }
        },
        "destination": {
          "address": destination,
          "minAmount": {
            "value": "1",
            "currency": "XRP"
          }
        }
      }, {
        signersCount: threshold
      })

    signatures.push(api.sign(tx.txJSON, signers[i].seed, {
      signAs: signers[i].address
    }).signedTransaction)
  }

  const combined = api.combine(signatures)
  console.log(combined.id)
  return await api.submit(combined.signedTransaction)
}

async function doMultiSign (account, secret, destination, nSigners, threshold) {
  try {

    await api.connect()

    let signers = []

    for (let i=0; i<nSigners; i++) {
      const seed = kp.generateSeed();
      const keypair = kp.deriveKeypair(seed);
      const address = kp.deriveAddress(keypair.publicKey);

      signers.push({
        address: address,
        seed: seed
      })
    }

    console.log(await addSigners(account, secret, signers, threshold))
    console.log(await sendPayment(account, destination, signers, threshold))
  } catch (err) {
    console.log(err)
  }
}

doMultiSign(
  'rDd6FpNbeY2CrQajSmP178BmNGusmQiYMM',
  'snyfcPrgMHCDR57M6Wrps8y6RPhiF',
  'rPT1Sjq2YGrBMTttX4GZHjKu9dyfzbpAYe',
  3, 2)