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

ES6 version of the [tweetnacl-js](https://github.com/dchest/tweetnacl-js) `nacl-fast.js`
Work in browser and in node (with "-r esm")

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

See [tweetnacl-js](https://github.com/dchest/tweetnacl-js)

Usage
-----

    import nacl from './tweetnacl-es6.js';

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)`,
instead of sharing: `Buffer.from(array.buffer)`, 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.

### Testing
----------

To run test in Node.js:

    $ npm run test-all

    $ npm run test-quick

To run itest in browser:

[browser test](https://hakanols.github.io/tweetnacl-es6/test/browser/index.html)

### Benchmarking

To run benchmarks in Node.js:

    $ npm run bench

To run itest in browser:

[browser benchmarks](https://hakanols.github.io/tweetnacl-es6/test/benchmark/bench.html)

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

See AUTHORS.md file.