1  const web3EthAccounts = require("web3-eth-accounts");
 2  const web3Utils = require("web3-utils");
 3  const cryptoRandomString = require("crypto-random-string");
 4  const stripHexPrefix = require("strip-hex-prefix");
 5  
 6  const isSignatureValid = (address, message, signature) => {
 7    const accounts = new web3EthAccounts();
 8    address = web3Utils.toChecksumAddress(address);
 9    let recoverAddress = accounts.recover(message, signature);
10    recoverAddress = web3Utils.toChecksumAddress(recoverAddress);
11    return address === recoverAddress;
12  };
13  
14  const getToken = () => {
15    const expirationTime = new Date();
16    expirationTime.setUTCHours(expirationTime.getUTCHours() + 2);
17    return {
18      token: cryptoRandomString({ length: 100, type: "hex" }),
19      expirationTime
20    };
21  };
22  
23  const hexValidator = value => {
24    const regex = /^[0-9A-Fa-f]*$/g;
25    if (regex.test(stripHexPrefix(value))) {
26      return true;
27    }
28    throw new Error("Invalid hex string");
29  };
30  
31  module.exports = {
32    isSignatureValid,
33    getToken,
34    hexValidator
35  };