bcrypt

What is bcrypt?

The bcrypt npm package is a library for hashing and comparing passwords securely in Node.js. It implements the bcrypt password-hashing function, which is designed to build a cryptographic hash of a user's password. Bcrypt is widely used due to its security features and resistance to brute-force attacks.

What are bcrypt's main functionalities?

Hashing Passwords

This feature allows you to securely hash a plaintext password. The 'saltRounds' parameter defines the cost factor for the hashing process, which determines the amount of time required to calculate a single bcrypt hash.

const bcrypt = require('bcrypt');
const saltRounds = 10;
const myPlaintextPassword = 's0/\/\P4$$w0rD';

bcrypt.hash(myPlaintextPassword, saltRounds, function(err, hash) {
  // Store hash in your password DB.
});

Comparing Passwords

This feature is used to compare a plaintext password against a previously hashed one to check if they match. It is commonly used during the login process to validate user credentials.

const bcrypt = require('bcrypt');
const myPlaintextPassword = 's0/\/\P4$$w0rD';
const someOtherPlaintextPassword = 'not_bacon';
const hash = '$2b$10$N9qo8uLOickgx2ZMRZoMyeIjZAgcfl7p92ldGxad68LJZdL17lhWy';

bcrypt.compare(myPlaintextPassword, hash, function(err, result) {
  // result == true
});

bcrypt.compare(someOtherPlaintextPassword, hash, function(err, result) {
  // result == false
});

Other packages similar to bcrypt

argon2

Argon2 is another password hashing library that won the Password Hashing Competition and is recommended for new applications. It is considered to be more resistant to GPU cracking attacks compared to bcrypt.

scrypt

Scrypt is a password-based key derivation function that is designed to be costly in both time and memory, making it hard to perform large-scale custom hardware attacks. It is similar to bcrypt but with a focus on memory-intensiveness.

pbkdf2

PBKDF2 (Password-Based Key Derivation Function 2) is part of RSA Laboratories' Public-Key Cryptography Standards (PKCS) series, and it's widely used for password hashing. It's not as secure as bcrypt for password storage because it's more vulnerable to GPU attacks.

README

node.bcrypt.js

Lib to help you hash passwords. bcrypt on wikipedia

Catalyst for this module: How To Safely Store A Password

If You Are Submitting Bugs/Issues

First, make sure that the version of node you are using is a stable version. You'll know this because it'll have an even major release number. We do not currently support unstable versions and while the module may happen to work on some unstable versions you'll find that we quickly close issues if you're not using a stable version.

If you are on a stable version of node, we can't magically know what you are doing to expose an issue, it is best if you provide a snippet of code or log files if you're having an install issue. This snippet need not include your secret sauce, but it must replicate the issue you are describing. The issues that get closed without resolution tend to be the ones that don't help us help you. Thanks.

Version Compatibility

Node Version	Bcrypt Version
0.4.x	<= 0.4.x
0.6.x	>= 0.5.x
0.8.x	>= 0.5.x
0.10.x	>= 0.5.x
0.11.x	>= 0.8.x

Windows users should make sure to have at least node 0.8.5 installed and version >= 0.7.1 of this module.

node-gyp only works with stable/released versions of node. Since the bcrypt module uses node-gyp to build and install you'll need a stable version of node to use bcrypt. If you do not you'll likely see an error that starts with:

gyp ERR! stack Error: "pre" versions of node cannot be installed, use the --nodedir flag instead

Security Issues/Concerns

Per bcrypt implementation, only the first 72 characters of a string are used. Any extra characters are ignored when matching passwords.

As should be the case with any security tool, this library should be scrutinized by anyone using it. If you find or suspect an issue with the code- please bring it to my attention and I'll spend some time trying to make sure that this tool is as secure as possible.

To make it easier for people using this tool to analyze what has been surveyed, here is a list of BCrypt related security issues/concerns as they've come up.

• An issue with passwords was found with a version of the Blowfish algorithm developed for John the Ripper. This is not present in the OpenBSD version and is thus not a problem for this module. HT zooko.

Dependencies

• NodeJS
• node-gyp
• Please check the dependencies for this tool at: https://github.com/nodejs/node-gyp
• Windows users will need the options for c# and c++ installed with their visual studio instance.
• Python 2.x
• OpenSSL - This is only required to build the bcrypt project if you are using versions <= 0.7.7. Otherwise, we're using the builtin node crypto bindings for seed data (which use the same OpenSSL code paths we were, but don't have the external dependency).

Install via NPM

npm install bcrypt

Note: OS X users using Xcode 4.3.1 or above may need to run the following command in their terminal prior to installing if errors occur regarding xcodebuild: sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer

Usage

async (recommended)

var bcrypt = require('bcrypt');
const saltRounds = 10;
const myPlaintextPassword = 's0/\/\P4$$w0rD';
const someOtherPlaintextPassword = 'not_bacon';

To hash a password:

Technique 1 (generate a salt and hash on separate function calls):

bcrypt.genSalt(saltRounds, function(err, salt) {
    bcrypt.hash(myPlaintextPassword, salt, function(err, hash) {
        // Store hash in your password DB.
    });
});

Technique 2 (auto-gen a salt and hash):

bcrypt.hash(myPlaintextPassword, saltRounds, function(err, hash) {
  // Store hash in your password DB.
});

Note that both techniques achieve the same end-result.

To check a password:

// Load hash from your password DB.
bcrypt.compare(myPlaintextPassword, hash, function(err, res) {
    // res == true
});
bcrypt.compare(someOtherPlaintextPassword, hash, function(err, res) {
    // res == false
});

sync

var bcrypt = require('bcrypt');
const saltRounds = 10;
const myPlaintextPassword = 's0/\/\P4$$w0rD';
const someOtherPlaintextPassword = 'not_bacon';

To hash a password:

Technique 1 (generate a salt and hash on separate function calls):

var salt = bcrypt.genSaltSync(saltRounds);
var hash = bcrypt.hashSync(myPlaintextPassword, salt);
// Store hash in your password DB.

Technique 2 (auto-gen a salt and hash):

var hash = bcrypt.hashSync(myPlaintextPassword, saltRounds);
// Store hash in your password DB.

As with async, both techniques achieve the same end-result.

To check a password:

// Load hash from your password DB.
bcrypt.compareSync(myPlaintextPassword, hash); // true
bcrypt.compareSync(someOtherPlaintextPassword, hash); // false

API

BCrypt.

• genSaltSync(rounds)
  • rounds - [OPTIONAL] - the cost of processing the data. (default - 10)
• genSalt(rounds, cb)
  • rounds - [OPTIONAL] - the cost of processing the data. (default - 10)
  • cb - [REQUIRED] - a callback to be fired once the salt has been generated. uses eio making it asynchronous.
    • err - First parameter to the callback detailing any errors.
    • salt - Second parameter to the callback providing the generated salt.
• hashSync(data, salt)
  • data - [REQUIRED] - the data to be encrypted.
  • salt - [REQUIRED] - the salt to be used to hash the password. if specified as a number then a salt will be generated with the specified number of rounds and used (see example under Usage).
• hash(data, salt, cb)
  • data - [REQUIRED] - the data to be encrypted.
  • salt - [REQUIRED] - the salt to be used to hash the password. if specified as a number then a salt will be generated with the specified number of rounds and used (see example under Usage).
  • cb - [REQUIRED] - a callback to be fired once the data has been encrypted. uses eio making it asynchronous.
    • err - First parameter to the callback detailing any errors.
    • encrypted - Second parameter to the callback providing the encrypted form.
• compareSync(data, encrypted)
  • data - [REQUIRED] - data to compare.
  • encrypted - [REQUIRED] - data to be compared to.
• compare(data, encrypted, cb)
  • data - [REQUIRED] - data to compare.
  • encrypted - [REQUIRED] - data to be compared to.
  • cb - [REQUIRED] - a callback to be fired once the data has been compared. uses eio making it asynchronous.
    • err - First parameter to the callback detailing any errors.
    • same - Second parameter to the callback providing whether the data and encrypted forms match [true | false].
• getRounds(encrypted) - return the number of rounds used to encrypt a given hash
  • encrypted - [REQUIRED] - hash from which the number of rounds used should be extracted.

A Note on Rounds

A note about the cost. When you are hashing your data the module will go through a series of rounds to give you a secure hash. The value you submit there is not just the number of rounds that the module will go through to hash your data. The module will use the value you enter and go through 2^rounds iterations of processing.

From @garthk, on a 2GHz core you can roughly expect:

rounds=8 : ~40 hashes/sec
rounds=9 : ~20 hashes/sec
rounds=10: ~10 hashes/sec
rounds=11: ~5  hashes/sec
rounds=12: 2-3 hashes/sec
rounds=13: ~1 sec/hash
rounds=14: ~1.5 sec/hash
rounds=15: ~3 sec/hash
rounds=25: ~1 hour/hash
rounds=31: 2-3 days/hash

Hash Info

The characters that comprise the resultant hash are ./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$.

Resultant hashes will be 60 characters long.

Testing

If you create a pull request, tests better pass :)

npm install
npm test

Credits

The code for this comes from a few sources:

• blowfish.cc - OpenBSD
• bcrypt.cc - OpenBSD
• bcrypt::gen_salt - gen_salt inclusion to bcrypt
• bcrypt_node.cc - me

Contributors

• Antonio Salazar Cardozo - Early MacOS X support (when we used libbsd)
• Ben Glow - Fixes for thread safety with async calls
• Van Nguyen - Found a timing attack in the comparator
• NewITFarmer - Initial Cygwin support
• David Trejo - packaging fixes
• Alfred Westerveld - packaging fixes
• Vincent Côté-Roy - Testing around concurrency issues
• Lloyd Hilaiel - Documentation fixes
• Roman Shtylman - Code refactoring, general rot reduction, compile options, better memory management with delete and new, and an upgrade to libuv over eio/ev.
• Vadim Graboys - Code changes to support 0.5.5+
• Ben Noordhuis - Fixed a thread safety issue in nodejs that was perfectly mappable to this module.
• Nate Rajlich - Bindings and build process.
• Sean McArthur - Windows Support
• Fanie Oosthuysen - Windows Support

License

Unless stated elsewhere, file headers or otherwise, the license as stated in the LICENSE file.

Changelog

0.8.7 (2016-06-09)

• update nan to 2.3.5 for improved node v6 support