Basic - Signing with a multi-sig account

This tutorial aims to show how to sign with a multi-sig account. This will be done by sending some assets from a multi-sig account.

A multi-sig Account can be identified by its verification script. It uses the CHECKMULTISIG OpCode (ae in hexstring). Thus, if you see any verification scripts ending with ae, it is likely to be a multi-sig Account.

Setup

Here I will assume that you have already sent some assets over to the multi-sig account.

const { default: Neon, api, wallet, tx, rpc } = require("@cityofzion/neon-js");

const neoscan = new api.neoscan.instance(
  "https://neoscan-testnet.io/api/main_net"
);
const rpcNodeUrl = "http://seed2.neo.org:20332";

Our multi-sig account in this example is made up of 3 keys with a signing threshold of 2. Do note that the order of keys in the array matters. A different order will generate a totally different address.

const keyA = new wallet.Account(
  "7d128a6d096f0c14c3a25a2b0c41cf79661bfcb4a8cc95aaaea28bde4d732344"
);
const keyB = new wallet.Account(
  "9ab7e154840daca3a2efadaf0df93cd3a5b51768c632f5433f86909d9b994a69"
);
const keyC = new wallet.Account(
  "3edee7036b8fd9cef91de47386b191dd76db2888a553e7736bb02808932a915b"
);

const multisigAcct = wallet.Account.createMultiSig(2, [
  keyA.publicKey,
  keyB.publicKey,
  keyC.publicKey,
]);

console.log("\n\n--- Multi-sig ---");
console.log(`My multi-sig address is ${multisigAcct.address}`);
console.log(
  `My multi-sig verificationScript is ${multisigAcct.contract.script}`
);

Construct Transaction

Similar to how we setup a transaction for a normal account transfer, we also do the same for our transfer from a multi-sig account.

var constructTx = neoscan.getBalance(multisigAcct.address).then((balance) => {
  const transaction = Neon.create
    .contractTx()
    .addIntent("NEO", 1, keyA.address)
    .addIntent("GAS", 0.00000001, keyB.address)
    .calculate(balance);

  return transaction;
});

Sign Transaction

The only difference is in the signing of transactions. We need to sign the transaction individually by each key first. Then, we combine the signatures together to form a multi-sig witness. We should only see 1 witness attached to the transaction.

const signTx = constructTx.then((transaction) => {
  const txHex = transaction.serialize(false);

  // This can be any 2 out of the 3 keys.
  const sig1 = wallet.sign(txHex, keyB.privateKey);
  const sig2 = wallet.sign(txHex, keyC.privateKey);

  const multiSigWitness = tx.Witness.buildMultiSig(
    txHex,
    [sig1, sig2],
    multisigAcct
  );

  transaction.addWitness(multiSigWitness);

  console.log("\n\n--- Transaction ---");
  console.log(JSON.stringify(transaction.export(), undefined, 2));

  console.log("\n\n--- Transaction hash---");
  console.log(transaction.hash);

  console.log("\n\n--- Transaction string ---");
  console.log(transaction.serialize(true));
  return transaction;
});

Send Transaction

We send off the transaction using sendrawtransaction RPC call like any other normal transaction.

const sendTx = signTx
  .then((transaction) => {
    const client = new rpc.RPCClient(rpcNodeUrl);
    return client.sendRawTransaction(transaction.serialize(true));
  })
  .then((res) => {
    console.log("\n\n--- Response ---");
    console.log(res);
  })
  .catch((err) => console.log(err));