Ethereum: Sign an offline transaction

sign-offline.js

#!/usr/bin/env node
'use strict';

// ethereum: generate signed transactions

const fs        = require('fs-extra');
const rls       = require('readline-sync');
const Accounts  = require('web3-eth-accounts');
const web3utils = require('web3-utils');
const accounts  = new Accounts();

async function main() {
	if (process.argv.length < 6) {
		console.log("usage:\n" +
			"\tsign-offline.js filename recipient amount nonce gasprice\n\n" +
			"\t\t amount is given in ether, gas price is given in gwei");
		process.exit(1);
	}

	let filename  = process.argv[2];
	let recipient = process.argv[3];
	let amount    = web3utils.toWei(process.argv[4], "ether");
	let nonce     = process.argv[5];
	let gasprice  = web3utils.toWei(process.argv[6], "gwei");

	console.log("file %s to %s amount %f eth nonce %d price %f",
		filename, recipient, amount, nonce, gasprice);

	let keystore = await fs.readJson(filename);

	if (!("crypto" in keystore)) {
		// MEW creates capitalized "crypto" property
		// web3 expects it in lowercase
		keystore.crypto = keystore.Crypto;
		delete keystore.Crypto;
	}

	let password  = rls.question('keystore Password? ', { hideEchoBack: true });
	let myaccount = accounts.decrypt(keystore, password);
	let data      = accounts.signTransaction({
		to: recipient,
		value: amount,
		gas: 21000,
		gasPrice: gasprice,
		nonce: nonce,
		chainId: 1 // mainNet
	}, myaccount.privateKey);
	console.log("signed raw transaction: ", data.rawTransaction);
}

main();