Improvements to make it public

[AlexGavrilov939]

1. config.json
Use Environment Variables: For better security, consider using environment variables instead of storing sensitive data (like private keys) in plaintext. This can be managed with libraries like dotenv, which load environment variables from a

.env file:

PRIVATE_KEY=your_private_key_here
NETWORK=testnet   # 'testnet' or 'bitcoin'

2. public-key.js

const { ECPairFactory, networks } = require('ecpair');
const tinysecp = require('tiny-secp256k1');
const { readFileSync } = require("fs");
const ECPair = ECPairFactory(tinysecp);
const config = JSON.parse(readFileSync('./config.json'));

const network = config.network === 'testnet' ? networks.testnet : networks.bitcoin;

console.log('Your public key is:', Buffer.from(ECPair.fromWIF(config.privateKey, network).publicKey).toString('hex'));

Notes:
Environment Variables: Replace config.json by accessing sensitive information directly from environment variables like process.env.PRIVATE_KEY.
Error Handling: Add checks to ensure PRIVATE_KEY and NETWORK are defined and valid to prevent runtime errors:

if (!process.env.PRIVATE_KEY) {
    console.error("Error: PRIVATE_KEY is missing.");
    process.exit(1);
}

Refactor to Functions: Wrap the logic in reusable functions to improve readability and facilitate testing:

function getPublicKey(privateKey, network) {
    return Buffer.from(ECPair.fromWIF(privateKey, network).publicKey).toString('hex');
}

3. sign.js

import { Psbt, initEccLib, networks } from 'bitcoinjs-lib';
import { signPsbtWithKeyPathAndScriptPath } from '@okxweb3/coin-bitcoin';
import { readFileSync } from 'fs';
import * as tinysecp from 'tiny-secp256k1';

initEccLib(tinysecp);
const config = JSON.parse(readFileSync('./config.json'));

const network = config.network === 'testnet' ? networks.testnet : networks.bitcoin;

const txHex = process.argv[2];
const psbtHex = signPsbtWithKeyPathAndScriptPath(txHex, config.privateKey, network);
const psbt = Psbt.fromHex(psbtHex, { network });
const signedTx = psbt.extractTransaction().toHex();

console.log('Signed Transaction Hex:', signedTx);

Notes:

Switch to Environment Variables: For security, avoid reading private keys directly from config.json. Access process.env.PRIVATE_KEY directly instead.
Input Validation: Check if txHex is provided and correctly formatted:

const txHex = process.argv[2];
if (!txHex) {
    console.error("Error: Transaction hex is missing.");
    process.exit(1);
}

Error Handling: Use a try-catch block to handle potential errors in the signing process:

try {
    const psbtHex = signPsbtWithKeyPathAndScriptPath(txHex, privateKey, network);
    const psbt = Psbt.fromHex(psbtHex, { network });
    const signedTx = psbt.extractTransaction().toHex();
    console.log('Signed Transaction Hex:', signedTx);
} catch (error) {
    console.error("Error signing transaction:", error.message);
}

Modularity: Refactor the signing logic into functions (e.g., signTransaction) to improve readability and ease testing.

4. Testing
Add Minimal Test Coverage: Implement basic unit tests for public-key.js and sign.js to cover core functionalities and edge cases. Using a testing framework like Jest or Mocha can simplify this process. Suggested tests include:
Public Key Generation: Check that the function returns the correct public key for a valid private key.
Transaction Signing: Validate that a provided transaction is correctly signed, including error handling for invalid input.

5. README.md Enhancements
Specify Compatibility: Mention the tested Node.js versions (e.g., v14.x, v16.x) and compatible operating systems (macOS, Ubuntu, Windows).

Recap:
Security Notes: It's better to use environment variables for sensitive data.
Error Handling: Document expected error messages for common issues (e.g., missing private key, invalid transaction hex).
Examples and Usage: Expand usage examples to guide users through setting up environment variables, running the library commands, and troubleshooting common issues.