@exodus/bip322-js/dist/BIP322.js

A Javascript library that provides utility functions related to the BIP-322 signature scheme

import { hashSync } from '@exodus/crypto/hash';
import * as bitcoin from '@exodus/bitcoinjs';
class BIP322 {
    static TAG = Buffer.from('BIP0322-signed-message');
    static hashMessage(message) {
        const tagHash = hashSync('sha256', this.TAG);
        return hashSync('sha256', [tagHash, tagHash, Buffer.from(message)]);
    }
    static buildToSpendTx(message, scriptPublicKey) {
        const psbt = new bitcoin.Psbt();
        psbt.setVersion(0);
        psbt.setLocktime(0);
        const messageHash = this.hashMessage(message);
        const scriptSigPartOne = new Uint8Array([0x00, 0x20]);
        const scriptSig = new Uint8Array(scriptSigPartOne.length + messageHash.length);
        scriptSig.set(scriptSigPartOne);
        scriptSig.set(messageHash, scriptSigPartOne.length);
        psbt.addInput({
            hash: '0'.repeat(64),
            index: 0xff_ff_ff_ff,
            sequence: 0,
            finalScriptSig: Buffer.from(scriptSig),
            witnessScript: Buffer.from([]),
        });
        psbt.addOutput({
            value: 0,
            script: scriptPublicKey,
        });
        return psbt.extractTransaction();
    }
    static buildToSignTx(toSpendTxId, witnessScript, isRedeemScript = false, tapInternalKey) {
        const psbt = new bitcoin.Psbt();
        psbt.setVersion(0);
        psbt.setLocktime(0);
        psbt.addInput({
            hash: toSpendTxId,
            index: 0,
            sequence: 0,
            witnessUtxo: {
                script: witnessScript,
                value: 0,
            },
        });
        if (isRedeemScript) {
            psbt.updateInput(0, {
                redeemScript: witnessScript,
            });
        }
        if (tapInternalKey) {
            psbt.updateInput(0, {
                tapInternalKey,
            });
        }
        psbt.addOutput({
            value: 0,
            script: Buffer.from([0x6a]),
        });
        return psbt;
    }
    static encodeWitness(signedPsbt) {
        const witness = signedPsbt.data.inputs[0]?.finalScriptWitness;
        if (witness) {
            return witness.toString('base64');
        }
        throw new Error('Cannot encode empty witness stack.');
    }
}
export default BIP322;