util.js

import { Router } from 'express';
import keythereum from 'keythereum';
import ethUtil from 'ethereumjs-util';

export default () => {
  const api = Router();

  api.post('/pk/to', async (req, res, next) => {
    const datadir = process.env.DATADIR_LOCAL;

    const address = req.body.address;
    const password = req.body.password;

    if (web3.utils.isAddress(address)) {
      const keyObject = keythereum.importFromFile(address, datadir);
      const privateKey = keythereum.recover(password, keyObject);

      res.status(200).json({
        code: 0,
        message: 'success',
        response: privateKey.toString('hex'),
      });
    } else {
      res.status(400).json({
        code: 1,
        message: 'invalid address format',
      });
    }
  });

  api.post('/pk/from', async (req, res, next) => {
    const pk = req.body.pk;
    const address = ethUtil.privateToAddress('0x' + pk);

    return res.status(200).json({
      code: 0,
      message: 'success',
      response: '0x' + address.toString('hex'),
    });
  });

  return api;
}