@vbyte/btc-dev/dist/lib/sighash/segwit.js

Batteries-included toolset for plebian bitcoin development

import { Buff } from '@vbyte/buff';
import { hash160, hash256 } from '@vbyte/micro-lib/hash';
import { Assert } from '@vbyte/micro-lib';
import { parse_txinput } from './util.js';
import { prefix_script_size, decode_script } from '../../lib/script/index.js';
import { encode_txin_vout, encode_tx_locktime, encode_txin_sequence, encode_txin_txid, encode_vout_value, encode_tx_version, parse_tx } from '../../lib/tx/index.js';
import * as CONST from '../../const.js';
export function hash_segwit_tx(txdata, options = {}) {
    const { sigflag = 0x01, txindex } = options;
    const tx = parse_tx(txdata);
    const is_anypay = (sigflag & 0x80) === 0x80;
    const flag = sigflag % 0x80;
    if (!CONST.SIGHASH_SEGWIT.includes(flag)) {
        throw new Error('Invalid hash type: ' + String(sigflag));
    }
    const { version, vin, vout, locktime } = tx;
    const txinput = parse_txinput(tx, options);
    const { txid, vout: prevIdx, prevout, sequence } = txinput;
    const { value } = prevout ?? {};
    if (value === undefined) {
        throw new Error('Prevout value is empty!');
    }
    let { pubkey, script } = options;
    if (script === undefined && pubkey !== undefined) {
        const pkhash = hash160(pubkey).hex;
        script = `76a914${String(pkhash)}88ac`;
    }
    if (script === undefined) {
        throw new Error('No pubkey / script has been set!');
    }
    if (decode_script(script).includes('OP_CODESEPARATOR')) {
        throw new Error('This library does not currently support the use of OP_CODESEPARATOR in segwit scripts.');
    }
    const sighash = [
        encode_tx_version(version),
        bip143_hash_prevouts(vin, is_anypay),
        bip143_hash_sequence(vin, flag, is_anypay),
        encode_txin_txid(txid),
        encode_txin_vout(prevIdx),
        prefix_script_size(script),
        encode_vout_value(value),
        encode_txin_sequence(sequence),
        bip143_hash_outputs(vout, flag, txindex),
        encode_tx_locktime(locktime),
        Buff.num(sigflag, 4).reverse()
    ];
    return hash256(Buff.join(sighash));
}
export function bip143_hash_prevouts(vin, isAnypay) {
    if (isAnypay === true) {
        return Buff.num(0, 32);
    }
    const stack = [];
    for (const { txid, vout } of vin) {
        stack.push(encode_txin_txid(txid));
        stack.push(encode_txin_vout(vout));
    }
    return hash256(Buff.join(stack));
}
export function bip143_hash_sequence(vin, sigflag, isAnyPay) {
    if (isAnyPay || sigflag !== 0x01) {
        return Buff.num(0, 32);
    }
    const stack = [];
    for (const { sequence } of vin) {
        stack.push(encode_txin_sequence(sequence));
    }
    return hash256(Buff.join(stack));
}
export function bip143_hash_outputs(vout, sigflag, idx) {
    const stack = [];
    if (sigflag === 0x01) {
        for (const { value, script_pk } of vout) {
            stack.push(encode_vout_value(value));
            stack.push(prefix_script_size(script_pk));
        }
        return hash256(Buff.join(stack));
    }
    if (sigflag === 0x03) {
        Assert.ok(idx !== undefined);
        if (idx < vout.length) {
            const { value, script_pk } = vout[idx];
            stack.push(encode_vout_value(value));
            stack.push(prefix_script_size(script_pk));
            return hash256(Buff.join(stack));
        }
    }
    return Buff.num(0, 32);
}