Email verification system

email-verification.js

const crypto = require('crypto');

const createError = (field, last = 'provided') => { throw Error(`${field} needs to be ${last}!`); };
const genHash = (secret, email, expiry, separator) => crypto.createHmac('sha256', secret).update(`${email}${separator}${expiry}`).digest('hex');

/**
 * @function createHash
 * @param {string} email - email
 * @param {string|number} secret - your secret (DO NOT PUBLISH IT)
 * @param {number|string} expiry - time in ms, when verification hash will be expired
 * @param {string} separator - custom separator between hash and expiry time
 * @returns {string} hash
 */
function createHash(email, secret, expiry = 60000, separator = '.') {
  if (!secret) createError('Secret');
  else if (!email) createError('Email');
  else if (!separator) createError('Separator');
  else if ((!expiry && String(expiry) !== '0') || (isNaN(expiry) && typeof expiry !== 'number')) createError('Expiry', 'a valid number');

  const expiryTime = Date.now() + expiry;
  return `${genHash(secret, email, expiryTime, separator)}${separator}${expiryTime}`;
}

/**
 * @function verifyHash
 * @param {string} hash - hash
 * @param {string} email - email
 * @param {string|number} secret - your secret (DO NOT PUBLISH IT)
 * @param {string} separator - custom separator between hash and expiry time
 * @returns {boolean} is hash valid
 */
function verifyHash(hash, email, secret, separator = '.') {
  if (!hash) createError('Hash');
  else if (!secret) createError('Secret');
  else if (!email) createError('Email');
  else if (!separator) createError('Separator');

  if (!hash.match(separator)) return false;
  const [baseHash, expiryTime] = hash.split(separator);
  if (expiryTime < Date.now()) {
    return false;
  }

  return genHash(secret, email, expiryTime, separator) === baseHash;
}

module.exports = {
  createHash,
  verifyHash,
};