@vbyte/btc-dev/dist/lib/taproot/cblock.js

Batteries-included toolset for plebian bitcoin development

import { Buff } from '@vbyte/buff';
import { Assert, ECC } from '@vbyte/micro-lib';
import { merkleize } from './tree.js';
import { TAPLEAF_DEFAULT_VERSION } from '../../const.js';
import * as Schema from '../../schema/index.js';
import { encode_tapbranch, encode_taptweak } from './encode.js';
import { parse_pubkey_parity, parse_cblock } from './parse.js';
const DEFAULT_VERSION = TAPLEAF_DEFAULT_VERSION;
export function create_taproot(config) {
    Schema.taproot.config.parse(config);
    const { pubkey, version = DEFAULT_VERSION } = config;
    const leaves = config.leaves ?? [];
    const target = (config.target !== undefined)
        ? Buff.bytes(config.target).hex
        : undefined;
    let path = [], taproot;
    if (leaves.length > 0) {
        const [root, _, proofs] = merkleize(leaves, target);
        path = proofs;
        taproot = root;
    }
    else {
        taproot = target;
    }
    const taptweak = encode_taptweak(pubkey, taproot);
    const twk_key = ECC.tweak_pubkey(pubkey, taptweak, 'ecdsa');
    const parity = parse_pubkey_parity(twk_key);
    const tapkey = ECC.serialize_pubkey(twk_key, 'bip340');
    const cbit = Buff.num(version + parity);
    const block = [cbit, Buff.bytes(pubkey)];
    if (path.length > 0) {
        path.forEach(e => block.push(e));
    }
    const cblock = Buff.join(block);
    return {
        int_key: Buff.bytes(pubkey).hex,
        path,
        parity,
        taproot: taproot ?? null,
        cblock: cblock.hex,
        tapkey: tapkey.hex,
        taptweak: taptweak.hex
    };
}
export function verify_taproot(tapkey, target, cblock) {
    Assert.size(tapkey, 32);
    const { parity, path, int_key } = parse_cblock(cblock);
    const ext_key = Buff.join([parity, tapkey]);
    let branch = Buff.bytes(target).hex;
    for (const leaf of path) {
        branch = encode_tapbranch(branch, leaf).hex;
    }
    const tap_tweak = encode_taptweak(int_key, branch);
    const tweaked_key = ECC.tweak_pubkey(int_key, tap_tweak, 'ecdsa');
    return (ext_key.hex === tweaked_key.hex);
}