Secure random token in Node.js

Question

In this question Erik needs to generate a secure random token in Node.js. There\'s the method crypto.randomBytes that generates a random Buffer. However, the ba

Answer 1

0. Using nanoid third party library [NEW!]

A tiny, secure, URL-friendly, unique string ID generator for JavaScript

https://github.com/ai/nanoid

import { nanoid } from "nanoid";
const id = nanoid(48);

1. Base 64 Encoding with URL and Filename Safe Alphabet

Page 7 of RCF 4648 describes how to encode in base 64 with URL safety. You can use an existing library like base64url to do the job.

The function will be:

var crypto = require('crypto');
var base64url = require('base64url');

/** Sync */
function randomStringAsBase64Url(size) {
  return base64url(crypto.randomBytes(size));
}

Usage example:

randomStringAsBase64Url(20);
// Returns 'AXSGpLVjne_f7w5Xg-fWdoBwbfs' which is 27 characters length.

Note that the returned string length will not match with the size argument (size != final length).

2. Crypto random values from limited set of characters

Beware that with this solution the generated random string is not uniformly distributed.

You can also build a strong random string from a limited set of characters like that:

var crypto = require('crypto');

/** Sync */
function randomString(length, chars) {
  if (!chars) {
    throw new Error('Argument \'chars\' is undefined');
  }

  var charsLength = chars.length;
  if (charsLength > 256) {
    throw new Error('Argument \'chars\' should not have more than 256 characters'
      + ', otherwise unpredictability will be broken');
  }

  var randomBytes = crypto.randomBytes(length);
  var result = new Array(length);

  var cursor = 0;
  for (var i = 0; i < length; i++) {
    cursor += randomBytes[i];
    result[i] = chars[cursor % charsLength];
  }

  return result.join('');
}

/** Sync */
function randomAsciiString(length) {
  return randomString(length,
    'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789');
}

Usage example:

randomAsciiString(20);
// Returns 'rmRptK5niTSey7NlDk5y' which is 20 characters length.

randomString(20, 'ABCDEFG');
// Returns 'CCBAAGDGBBEGBDBECDCE' which is 20 characters length.

Answer 2

https://www.npmjs.com/package/crypto-extra has a method for it :)

var value = crypto.random(/* desired length */)

Answer 3

crypto-random-string is a nice module for this.

const cryptoRandomString = require('crypto-random-string');
 
cryptoRandomString({length: 10});
// => '2cf05d94db'
 
cryptoRandomString({length: 10, type: 'base64'});
// => 'YMiMbaQl6I'
 
cryptoRandomString({length: 10, type: 'url-safe'});
// => 'YN-tqc8pOw'
 
cryptoRandomString({length: 10, type: 'numeric'});
// => '8314659141'
 
cryptoRandomString({length: 6, type: 'distinguishable'});
// => 'CDEHKM'
 
cryptoRandomString({length: 10, type: 'ascii-printable'});
// => '`#Rt8$IK>B'
 
cryptoRandomString({length: 10, type: 'alphanumeric'});
// => 'DMuKL8YtE7'
 
cryptoRandomString({length: 10, characters: 'abc'});
// => 'abaaccabac'

cryptoRandomString.async(options) add .async if you want to get a promise.

Answer 4

Check out:

var crypto = require('crypto');
crypto.randomBytes(Math.ceil(length/2)).toString('hex').slice(0,length);

Answer 5

Look at real_ates ES2016 way, it's more correct.

ECMAScript 2016 (ES7) way

import crypto from 'crypto';

function spawnTokenBuf() {
    return function(callback) {
        crypto.randomBytes(48, callback);
    };
}

async function() {
    console.log((await spawnTokenBuf()).toString('base64'));
};

Generator/Yield Way

var crypto = require('crypto');
var co = require('co');

function spawnTokenBuf() {
    return function(callback) {
        crypto.randomBytes(48, callback);
    };
}

co(function* () {
    console.log((yield spawnTokenBuf()).toString('base64'));
});

Answer 6

Simple function that gets you a token that is URL safe and has base64 encoding! It's a combination of 2 answers from above.

const randomToken = () => {
    crypto.randomBytes(64).toString('base64').replace(/\//g,'_').replace(/\+/g,'-');
}