basic_generate_hash&verify_password.js

const genRandomString = function(length){
  return crypto.randomBytes(Math.ceil(length/2))
          .toString('hex') /** convert to hexadecimal format */
          .slice(0,length);   /** return required number of characters */
};
const sha512 = function(password, salt){
  var hash = crypto.createHmac('sha512', salt); /** Hashing algorithm sha512 */
  hash.update(password);
  var value = hash.digest('hex');
  return {
      salt:salt,
      passwordHash:value
  };
};

exports.saltHashPassword = function (userpassword) {
  var salt = genRandomString(20); /** Gives us salt of length 16 */
  var passwordData = sha512(userpassword, salt);
  return passwordData;
  console.log('UserPassword = '+userpassword);
  console.log('Passwordhash = '+passwordData.passwordHash);
  console.log('nSalt = '+passwordData.salt);
}

/////////
////////
// Login
//SECRET KEY maybe anything

var jwt = require('jsonwebtoken');

exports.verifyPassword = function(password, salt){
  var hash = crypto.createHmac('sha512', salt); /** Hashing algorithm sha512 */
  hash.update(password);
  var value = hash.digest('hex');
  return value;
};
exports.generateToken = function(dataItem,SECRET_KEY){
  return jwt.sign({ email: dataItem.email }, SECRET_KEY);
}