npm package: @openpgp/tweetnacl
Description: Port of TweetNaCl cryptographic library to JavaScript
Author: TweetNaCl-js contributors
Latest version: 1.0.4-2

TweetNaCl.js
============

> This fork drops the functions that are not needed for OpenPGP.js, resulting in a lighter `nacl-fast.js` file.
We recommend you use the upstream repo. The rest of the README refers to the upstream library.

<hr>

Port of [TweetNaCl](http://tweetnacl.cr.yp.to) / [NaCl](http://nacl.cr.yp.to/)
to JavaScript for modern browsers and Node.js. Public domain.

Demo: <https://dchest.github.io/tweetnacl-js/>

Documentation
=============

* [Overview](#overview)
* [Audits](#audits)
* [Security Considerations](#security-considerations)
* [Installation](#installation)
* [Examples](#examples)
* [Usage](#usage)
  * [Public-key authenticated encryption (box)](#public-key-authenticated-encryption-box)
  * [Secret-key authenticated encryption (secretbox)](#secret-key-authenticated-encryption-secretbox)
  * [Scalar multiplication](#scalar-multiplication)
  * [Signatures](#signatures)
  * [Hashing](#hashing)
  * [Random bytes generation](#random-bytes-generation)
  * [Constant-time comparison](#constant-time-comparison)
* [System requirements](#system-requirements)
* [Development and testing](#development-and-testing)
* [Benchmarks](#benchmarks)
* [Contributors](#contributors)
* [Who uses it](#who-uses-it)


Overview
--------

The primary goal of this project is to produce a translation of TweetNaCl to
JavaScript which is as close as possible to the original C implementation, plus
a thin layer of idiomatic high-level API on top of it.

There are two versions, you can use either of them:

* `nacl.js` is the port of TweetNaCl with minimum differences from the
  original + high-level API.

* `nacl-fast.js` is like `nacl.js`, but with some functions replaced with
  faster versions. (Used by default when importing NPM package.)


Audits
------

TweetNaCl.js has been audited by [Cure53](https://cure53.de/) in January-February
2017 (audit was sponsored by [Deletype](https://deletype.com)):

> The overall outcome of this audit signals a particularly positive assessment
> for TweetNaCl-js, as the testing team was unable to find any security
> problems in the library.

[Read full audit report](https://cure53.de/tweetnacl.pdf)

While the audit didn't find any bugs, there has been [1 bug](https://github.com/dchest/tweetnacl-js/issues/187) discovered and fixed after the audit.


Security Considerations
-----------------------

It is important to note that TweetNaCl.js is a low-level library
that doesn't provide complete security protocols. When designing
protocols, you should carefully consider various properties of
underlying primitives.

### No secret key commitment

While XSalsa20-Poly1305, as used in `nacl.secretbox` and `nacl.box`,
meets the standard notions of privacy and authenticity for a secret-key
authenticated-encryption scheme using nonces, it is *not key-committing*,
which means that it is possible to find a ciphertext which decrypts to
valid plaintexts under two different keys. This may lead to vulnerabilities
if encrypted messages are used in a context where key commitment is expected.

### Signature malleability

While Ed22519 as originally defined and implemented in `nacl.sign`
meets the standard notion of unforgeability for a public-key
signature scheme under chosen-message attacks, it is *malleable*:
given a signed message, it is possible, without knowing the secret key,
to create a different signature for the same message that will verify
under the same public key. This may lead to vulnerabilities if
signatures are used in a context where malleability is not expected.

### Hash length-extension attacks

The SHA-512 hash function, as implemented by `nacl.hash`, is *not
resistant* to length-extension attacks.

### Side-channel attacks

While TweetNaCl.js uses algorithmic constant-time operations,
it is impossible to guarantee that they are physically constant time
given JavaScript runtimes, JIT compilers, and other factors.
It is also impossible to guarantee that secret data is physically
removed from memory during cleanup due to copying garbage
collectors and optimizing compilers.


Installation
------------

You can install TweetNaCl.js via a package manager:

[Yarn](https://yarnpkg.com/):

    $ yarn add tweetnacl

[NPM](https://www.npmjs.org/):

    $ npm install tweetnacl

or [download source code](https://github.com/dchest/tweetnacl-js/releases).


Examples
--------
You can find usage examples in our [wiki](https://github.com/dchest/tweetnacl-js/wiki/Examples).


Usage
-----

All API functions accept and return bytes as `Uint8Array`s.  If you need to
encode or decode strings, use functions from
<https://github.com/dchest/tweetnacl-util-js> or one of the more robust codec
packages.

In Node.js v4 and later `Buffer` objects are backed by `Uint8Array`s, so you
can freely pass them to TweetNaCl.js functions as arguments. The returned
objects are still `Uint8Array`s, so if you need `Buffer`s, you'll have to
convert them manually; make sure to convert using copying: `Buffer.from(array)`
(or `new Buffer(array)` in Node.js v4 or earlier), instead of sharing:
`Buffer.from(array.buffer)` (or `new Buffer(array.buffer)` Node 4 or earlier),
because some functions return subarrays of their buffers.


### Public-key authenticated encryption (box)

Implements *x25519-xsalsa20-poly1305*.

#### nacl.box.keyPair()

Generates a new random key pair for box and returns it as an object with
`publicKey` and `secretKey` members:

    {
       publicKey: ...,  // Uint8Array with 32-byte public key
       secretKey: ...   // Uint8Array with 32-byte secret key
    }


#### nacl.box.keyPair.fromSecretKey(secretKey)

Returns a key pair for box with public key corresponding to the given secret
key.

#### nacl.box(message, nonce, theirPublicKey, mySecretKey)

Encrypts and authenticates message using peer's public key, our secret key, and
the given nonce, which must be unique for each distinct message for a key pair.

Returns an encrypted and authenticated message, which is
`nacl.box.overheadLength` longer than the original message.

#### nacl.box.open(box, nonce, theirPublicKey, mySecretKey)

Authenticates and decrypts the given box with peer's public key, our secret
key, and the given nonce.

Returns the original message, or `null` if authentication fails.

#### nacl.box.before(theirPublicKey, mySecretKey)

Returns a precomputed shared key which can be used in `nacl.box.after` and
`nacl.box.open.after`.

#### nacl.box.after(message, nonce, sharedKey)

Same as `nacl.box`, but uses a shared key precomputed with `nacl.box.before`.

#### nacl.box.open.after(box, nonce, sharedKey)

Same as `nacl.box.open`, but uses a shared key precomputed with `nacl.box.before`.

#### Constants

##### nacl.box.publicKeyLength = 32

Length of public key in bytes.

##### nacl.box.secretKeyLength = 32

Length of secret key in bytes.

##### nacl.box.sharedKeyLength = 32

Length of precomputed shared key in bytes.

##### nacl.box.nonceLength = 24

Length of nonce in bytes.

##### nacl.box.overheadLength = 16

Length of overhead added to box compared to original message.


### Secret-key authenticated encryption (secretbox)

Implements *xsalsa20-poly1305*.

#### nacl.secretbox(message, nonce, key)

Encrypts and authenticates message using the key and the nonce. The nonce must
be unique for each distinct message for this key.

Returns an encrypted and authenticated message, which is
`nacl.secretbox.overheadLength` longer than the original message.

#### nacl.secretbox.open(box, nonce, key)

Authenticates and decrypts the given secret box using the key and the nonce.

Returns the original message, or `null` if authentication fails.

#### Constants

##### nacl.secretbox.keyLength = 32

Length of key in bytes.

##### nacl.secretbox.nonceLength = 24

Length of nonce in bytes.

##### nacl.secretbox.overheadLength = 16

Length of overhead added to secret box compared to original message.


### Scalar multiplication

Implements *x25519*.

#### nacl.scalarMult(n, p)

Multiplies an integer `n` by a group element `p` and returns the resulting
group element.

#### nacl.scalarMult.base(n)

Multiplies an integer `n` by a standard group element and returns the resulting
group element.

#### Constants

##### nacl.scalarMult.scalarLength = 32

Length of scalar in bytes.

##### nacl.scalarMult.groupElementLength = 32

Length of group element in bytes.


### Signatures

Implements [ed25519](http://ed25519.cr.yp.to).

#### nacl.sign.keyPair()

Generates new random key pair for signing and returns it as an object with
`publicKey` and `secretKey` members:

    {
       publicKey: ...,  // Uint8Array with 32-byte public key
       secretKey: ...   // Uint8Array with 64-byte secret key
    }

#### nacl.sign.keyPair.fromSecretKey(secretKey)

Returns a signing key pair with public key corresponding to the given
64-byte secret key. The secret key must have been generated by
`nacl.sign.keyPair` or `nacl.sign.keyPair.fromSeed`.

#### nacl.sign.keyPair.fromSeed(seed)

Returns a new signing key pair generated deterministically from a 32-byte seed.
The seed must contain enough entropy to be secure. This method is not
recommended for general use: instead, use `nacl.sign.keyPair` to generate a new
key pair from a random seed.

#### nacl.sign(message, secretKey)

Signs the message using the secret key and returns a signed message.

#### nacl.sign.open(signedMessage, publicKey)

Verifies the signed message and returns the message without signature.

Returns `null` if verification failed.

#### nacl.sign.detached(message, secretKey)

Signs the message using the secret key and returns a signature.

#### nacl.sign.detached.verify(message, signature, publicKey)

Verifies the signature for the message and returns `true` if verification
succeeded or `false` if it failed.

#### Constants

##### nacl.sign.publicKeyLength = 32

Length of signing public key in bytes.

##### nacl.sign.secretKeyLength = 64

Length of signing secret key in bytes.

##### nacl.sign.seedLength = 32

Length of seed for `nacl.sign.keyPair.fromSeed` in bytes.

##### nacl.sign.signatureLength = 64

Length of signature in bytes.


### Hashing

Implements *SHA-512*.

#### nacl.hash(message)

Returns SHA-512 hash of the message.

#### Constants

##### nacl.hash.hashLength = 64

Length of hash in bytes.


### Random bytes generation

#### nacl.randomBytes(length)

Returns a `Uint8Array` of the given length containing random bytes of
cryptographic quality.

**Implementation note**

TweetNaCl.js uses the following methods to generate random bytes,
depending on the platform it runs on:

* `window.crypto.getRandomValues` (WebCrypto standard)
* `window.msCrypto.getRandomValues` (Internet Explorer 11)
* `crypto.randomBytes` (Node.js)

If the platform doesn't provide a suitable PRNG, the following functions,
which require random numbers, will throw exception:

* `nacl.randomBytes`
* `nacl.box.keyPair`
* `nacl.sign.keyPair`

Other functions are deterministic and will continue working.

If a platform you are targeting doesn't implement secure random number
generator, but you somehow have a cryptographically-strong source of entropy
(not `Math.random`!), and you know what you are doing, you can plug it into
TweetNaCl.js like this:

    nacl.setPRNG(function(x, n) {
      // ... copy n random bytes into x ...
    });

Note that `nacl.setPRNG` *completely replaces* internal random byte generator
with the one provided.


### Constant-time comparison

#### nacl.verify(x, y)

Compares `x` and `y` in constant time and returns `true` if their lengths are
non-zero and equal, and their contents are equal.

Returns `false` if either of the arguments has zero length, or arguments have
different lengths, or their contents differ.


System requirements
-------------------

TweetNaCl.js supports modern browsers that have a cryptographically secure
pseudorandom number generator and typed arrays, including the latest versions
of:

* Chrome
* Firefox
* Safari (Mac, iOS)
* Internet Explorer 11

Other systems:

* Node.js


Development and testing
------------------------

Install NPM modules needed for development:

    $ npm install

To build minified versions:

    $ npm run build

Tests use minified version, so make sure to rebuild it every time you change
`nacl.js` or `nacl-fast.js`.

### Testing

To run tests in Node.js:

    $ npm run test-node

By default all tests described here work on `nacl.min.js`. To test other
versions, set environment variable `NACL_SRC` to the file name you want to test.
For example, the following command will test fast minified version:

    $ NACL_SRC=nacl-fast.min.js npm run test-node

To run full suite of tests in Node.js, including comparing outputs of
JavaScript port to outputs of the original C version:

    $ npm run test-node-all

To prepare tests for browsers:

    $ npm run build-test-browser

and then open `test/browser/test.html` (or `test/browser/test-fast.html`) to
run them.

To run tests in both Node and Electron:

    $ npm test

### Benchmarking

To run benchmarks in Node.js:

    $ npm run bench
    $ NACL_SRC=nacl-fast.min.js npm run bench

To run benchmarks in a browser, open `test/benchmark/bench.html` (or
`test/benchmark/bench-fast.html`).


Benchmarks
----------

For reference, here are benchmarks from MacBook Pro (Retina, 13-inch, Mid 2014)
laptop with 2.6 GHz Intel Core i5 CPU (Intel) in Chrome 53/OS X, Xiaomi Redmi
Note 3 smartphone with 1.8 GHz Qualcomm Snapdragon 650 64-bit CPU (ARM) in
Chrome 52/Android, and MacBook Air 2020 with Apple M1 SOC (M1) in Chromium 102/macOS.

|               | nacl.js Intel | nacl-fast.js Intel  |   nacl.js ARM | nacl-fast.js ARM  | nacl-fast.js M1   |
| ------------- |:-------------:|:-------------------:|:-------------:|:-----------------:|:-----------------:|
| salsa20       | 1.3 MB/s      | 128 MB/s            |  0.4 MB/s     |  43 MB/s          |  268 MB/s         |
| poly1305      | 13 MB/s       | 171 MB/s            |  4 MB/s       |  52 MB/s          |  248 MB/s         |
| hash          | 4 MB/s        | 34 MB/s             |  0.9 MB/s     |  12 MB/s          |  76 MB/s          |
| secretbox 1K  | 1113 op/s     | 57583 op/s          |  334 op/s     |  14227 op/s       |  54546 op/s       |
| box 1K        | 145 op/s      | 718 op/s            |  37 op/s      |  368 op/s         |  1836 op/s        |
| scalarMult    | 171 op/s      | 733 op/s            |  56 op/s      |  380 op/s         |  1882 op/s        |
| sign          | 77  op/s      | 200 op/s            |  20 op/s      |  61 op/s          |  592 op/s         |
| sign.open     | 39  op/s      | 102  op/s           |  11 op/s      |  31 op/s          |  300 op/s         |

(You can run benchmarks on your devices by clicking on the links at the bottom
of the [home page](https://tweetnacl.js.org)).

In short, with *nacl-fast.js* and 1024-byte messages you can expect to encrypt and
authenticate more than 57000 messages per second on a typical laptop or more than
14000 messages per second on a $170 smartphone, sign about 500 and verify 300
messages per second on a laptop or 60 and 30 messages per second on a smartphone,
per CPU core (with Web Workers you can do these operations in parallel),
which is good enough for most applications.


Contributors
------------

See AUTHORS.md file.


Third-party libraries based on TweetNaCl.js
-------------------------------------------

* [chloride](https://github.com/dominictarr/chloride) - unified API for various NaCl modules
* [forward-secrecy](https://github.com/alax/forward-secrecy) — Axolotl ratchet implementation
* [nacl-stream](https://github.com/dchest/nacl-stream-js) - streaming encryption
* [ristretto255-js](https://github.com/calibra/ristretto255-js) — implementation of the [ristretto255 group](https://ristretto.group/)
* [tweetnacl-auth-js](https://github.com/dchest/tweetnacl-auth-js) — implementation of [`crypto_auth`](http://nacl.cr.yp.to/auth.html)
* [tweetnacl-js-sealed-box](https://github.com/TogaTech/tweetnacl-js-sealed-box) — fork that adds [`sealed boxes`](https://download.libsodium.org/doc/public-key_cryptography/sealed_boxes.html)
* [ed2curve](https://github.com/dchest/ed2curve-js) — convert Ed25519 signing key pair to X25519 boxes key pair


Who uses it
-----------

Some notable users of TweetNaCl.js are listed on the [associated wiki page](https://github.com/dchest/tweetnacl-js/wiki/Who-uses-TweetNaCl.js).