neurai-sign-transaction

Signs a Neurai transaction

The sole purpose of this project is to enable us to "Sign XNA or asset transfer transactions in pure JavaScript"

Working proof of concept.

We are able to sign Neurai asset transfers using bitcoinjs-lib version 5.2 with a patched Transaction Builder.

How to use

The sign method has four arguments

1. The network "string", can be "xna" | "xna-test" | "evr" | "evr-test",
2. The raw transaction (in hex)
3. An array of UTXO objects to use
4. Private keys. An object with "address" as key and "WIF" as value

returns a signed transaction (hex), after that it is up to you to publish it on the network

import Signer from "@neuraiproject/neurai-sign-transaction";

const raw =
  "0200000002fe6cfe20184b592849231eea8167e3de073b6ec1b8218c2ef36838a4e07dd11c0200000000ffffffff28c32b825b14251708ea39c0ac706bd3d933778d7838d01b678b045a48e219950000000000ffffffff0200000000000000003a76a91416014dfb02a07417cbf8c0366ee5ae0a29d5878f88acc01e72766e74114652454e2f59554c45544944453230323100e1f5050000000075000e2707000000001976a914c6a0e8557c7567a4d9cc84574c34fbb62ece3c9688ac00000000";
const UTXOs = [
  {
    address: "RTPSdYw3iB93L6Hb9xWd1ixVxPYu1QePdi",
    assetName: "XNA",
    txid: "1cd17de0a43868f32e8c21b8c16e3b07dee36781ea1e234928594b1820fe6cfe",
    outputIndex: 2,
    script: "76a914c6a0e8557c7567a4d9cc84574c34fbb62ece3c9688ac",
    satoshis: 122000000,
    height: 2670673,
  },
  {
    address: "RSuQSgXXr1z4gKommSqhHLffiNxnSE3Bwn",
    assetName: "FREN/YULETIDE2021",
    txid: "9519e2485a048b671bd038788d7733d9d36b70acc039ea081725145b822bc328",
    outputIndex: 0,
    script:
      "76a914c1536f46fa2fa04be210406529be283c1c85e4ce88acc01e72766e74114652454e2f59554c45544944453230323100e1f5050000000075",
    satoshis: 100000000,
    height: 2670669,
  },
];
const privateKeys = {
  RTPSdYw3iB93L6Hb9xWd1ixVxPYu1QePdi:
    "L2GD7txjmdKSTy7mBq2FowZusjdWP679ttWSRfj4eLBu2usTWMV9",
  RSuQSgXXr1z4gKommSqhHLffiNxnSE3Bwn:
    "Kxj2xMvLbcXeGzuSrZLtpnZWzXnTXnhtuCQRQhKLjN7bSQXuakyh",
};
const signed = Signer.sign("xna", raw, UTXOs, privateKeys);
console.log(signed);

What we need

We need code that can take the UNSIGNED transaction, and sign it using the private keys. This transaction transfers one FREN/CIVILAZATION asset/token and pays fees in XNA.

decoded UNSIGNED transaction

decoded SIGNED transaction

Private keys

Important stuff learned

• Signing a transaction means, sign the inputs to the transaction and sign the whole transaction.

• To sign a transaction, inputs and outputs are not enough, we need the UTXOs used (to get each utxo.script)

• bitcoinjs-lib cant sign an unsigned transaction from Neurai out of the box because of this line in transaction_builder.js

  const prevOutScript = payments.p2pkh({ pubkey: ourPubKey }).output;

  That is, transaction_builder assumes that the previous outputscript was "just" our pub key/address, that is not true in the case of Neurai asset transfer transactions.

Stuff to look at

https://github.com/bitpay/bitcore-lib/blob/master/lib/script/script.js