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Hash passwords the right way (Argon2 & bcrypt support)

Hashy is small Node.js library which aims to do passwords hashing the correct way.

It has been heavily inspired by the new PHP password hashing API but, following the Node.js philosophy, hashing is done asynchronously.

Furthermore, to make the interfaces as easy to use as possible, async functions can either be used with callbacks or they return promises which will make them super easy to work with async functions!

Supported algorithms:

Why a new library?

The other ones I found were too complicated and/or were missing important features.

The main missing feature is the needRehash() function: cryptography is a fast-moving science and algorithms can quickly become obsolete or their parameters needs to be adjusted to compensate the performance increase of recent computers (e.g. bcrypt cost factor).

This is exactly what this function is for: checking whether a hash uses the correct algorithm (and options) to see if we need to compute a new hash for this password.


Installation of the npm package:

> npm install --save hashy

Hashy requires promises support, for Node versions prior to 0.12 see this page to enable them.

How to use it?

First, you may take a look at examples: using callbacks, promises or async functions (requires Node >= 7.6).

Creating a hash

hashy.hash(password, function (error, hash) {
  if (error) {
    return console.log(error);

  console.log("generated hash: ", hash);

hash() handles additionaly two parameters which may be passed before the callback:

  1. algo: which algorithm to use, it defaults to 'bcrypt';
  2. options: additional options for the current algorithm, for bcrypt it defaults to {cost: 10}..

Checking a password against a hash

hashy.verify(password, hash, function (error, success) {
  if (error) {
    return console.error(err);

  if (success) {
    console.log("you are now authenticated!");
  } else {
    console.warn("invalid password!");

Getting information about a hash

const info = hashy.getInfo(hash);

Checking whether a hash is up to date

As I said earlier, we must be able to check whether the hash is up to date, i.e. if it has been generated by the last algorithm available with the last set of options.

if (hashy.needsRehash(hash)) {
  // Rehash.

It handles the optional algo and options parameters like hash().

Changing default options.

The default options for a given algorithm is available at hashy.options[>algo<].

// Sets the default cost for bcrypt to 12.
hashy.options.bcrypt.cost = 12;

Using promises

Same interface as above but without the callbacks!

// Hashing.
hashy.hash(password).then(function (hash) {
  console.log('generated hash:' hash)

// Checking.
hashy.verify(password, hash).then(function (success) {
  if (success) {
    console.log('you are now authenticated!')
  } else {
    console.warn('invalid password!')

As you can see, you don't even have to handle errors if you don't want to!

Using async functions

Note: only available since Node.js 7.6.

Same interface as promises but much more similar to a synchronous code!

// Hashing.
(async function () {
  const hash = await hashy.hash(password);
  console.log("generated hash:", hash);
  // Checking.
  async function () {
    if (await hashy.verify(password, hash)) {
      console.log("you are now authenticated!");
    } else {
      console.warn("invalid password!");


Contributions are very welcome, either on the documentation or on the code.

You may:

  • report any issue you've encountered;
  • fork and create a pull request.


Hashy is released under the MIT license.

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  • julien-f
  • marsaud
  • pdonias