play2.mjs

import { BIP32Factory } from 'bip32';
import { ECPairFactory } from 'ecpair'
import * as ecc from 'tiny-secp256k1';

import * as bitcoin from './src/index.js';
import { testnet as network } from './src/networks.js'

const ECPair = ECPairFactory(ecc);
const bip32 = BIP32Factory(ecc);
const hex = (s) => Buffer.from(s, 'hex')

// Order of the curve (N) - 1
const N_LESS_1 = Buffer.from(
    'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364140',
    'hex',
);
// 1 represented as 32 bytes BE
const ONE = Buffer.from(
    '0000000000000000000000000000000000000000000000000000000000000001',
    'hex',
);


const myKey = ECPair.fromPrivateKey(hex('accaf12e04e11b08fc28f5fe75b47ea663843b698981e31f1cafa2224d6e28c0'))
const output = createKeySpendOutput(myKey.publicKey);
const address = bitcoin.address.fromOutputScript(output, network);
const amount = 100000;
const sendAmount = 75000
console.log('### output', output.toString('hex'))
console.log('### address', address)

const unspent = { txId: '8162b0310f37182049429e147b0ba7ac17eb4dd5c6d3016927e4c993b63edc2b', vout: 0}

const tx = createSigned(
  myKey,
  unspent.txId,
  unspent.vout,
  sendAmount,
  [output], // public key
  [amount],
);

const txHex = tx.toHex();
console.log('### txHex', txHex)
// txId: a618fdb361a6cfbc345d2b030ab7533dc88b3c097af58df6979b4d9aa4472379


function createKeySpendOutput(publicKey) {
    // x-only pubkey (remove 1 byte y parity)
    const myXOnlyPubkey = publicKey.slice(1, 33);
    const commitHash = bitcoin.crypto.taggedHash('TapTweak', myXOnlyPubkey);
    console.log('### commitHash ', commitHash.toString('hex'))
    const tweakResult = ecc.xOnlyPointAddTweak(myXOnlyPubkey, commitHash);
    console.log('### tweakResult xOnlyPubkey', Buffer.from(tweakResult.xOnlyPubkey).toString('hex'))
    if (tweakResult === null) throw new Error('Invalid Tweak');
    const { xOnlyPubkey: tweaked } = tweakResult;
    // scriptPubkey
    return Buffer.concat([
        // witness v1, PUSH_DATA 32 bytes
        Buffer.from([0x51, 0x20]),
        // x-only tweaked pubkey
        tweaked,
    ]);
}

function signTweaked(messageHash, key) {
    const privateKey =
        key.publicKey[0] === 2
            ? key.privateKey
            : ecc.privateAdd(ecc.privateSub(N_LESS_1, key.privateKey), ONE);
    const tweakHash = bitcoin.crypto.taggedHash(
        'TapTweak',
        key.publicKey.slice(1, 33),
    );
    const newPrivateKey = ecc.privateAdd(privateKey, tweakHash);
    if (newPrivateKey === null) throw new Error('Invalid Tweak');
    return ecc.signSchnorr(messageHash, newPrivateKey, Buffer.alloc(32));
}

// Function for creating signed tx
function createSigned(
    key,
    txid,
    vout,
    amountToSend,
    scriptPubkeys,
    values,
  ) {
      console.log('### scriptPubkeys', scriptPubkeys.map(s => s.toString('hex')))
      console.log('### values', values)
    const tx = new bitcoin.Transaction();
    tx.version = 2;
    // Add input
    tx.addInput(Buffer.from(txid, 'hex').reverse(), vout);
    // Add output
    tx.addOutput(scriptPubkeys[0], amountToSend);
    const sighash = tx.hashForWitnessV1(
      0, // which input
      scriptPubkeys, // All previous outputs of all inputs
      values, // All previous values of all inputs
      bitcoin.Transaction.SIGHASH_DEFAULT, // sighash flag, DEFAULT is schnorr-only (DEFAULT == ALL)
    );
    console.log('### sighash', sighash.toString('hex'))
    console.log('### unsignedTx', tx.toHex())
    const signature = Buffer.from(signTweaked(sighash, key));
    // witness stack for keypath spend is just the signature.
    // If sighash is not SIGHASH_DEFAULT (ALL) then you must add 1 byte with sighash value
    tx.ins[0].witness = [signature];
    return tx;
  }