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libsodium

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libsodium.js

Overview

The sodium crypto library compiled to pure JavaScript using Emscripten, with automatically generated wrappers to make it easy to use in web applications.

The complete library weights 115 Kb (minified, gzipped) and can run in a web browser as well as server-side.

Compatibility

Supported browsers/JS engines:

  • Chrome >= 16
  • Edge >= 0.11
  • Firefox >= 21
  • Internet Explorer >= 11
  • Mobile Safari on iOS >= 8.0 (older versions produce incorrect results)
  • NodeJS
  • Opera >= 15
  • Safari >= 6 (older versions produce incorrect results)

Installation

Ready-to-use files based on libsodium 1.0.13 can be directly copied to your project.

Usage with global definitions, for web browsers

Use Bower:

$ bower install libsodium.js

or directly include a copy of the sodium.min.js file.

Alternatively, for better performance and to avoid including a local copy, libsodium.js is available on cdnjs.

Including the sodium.min.js file will add a sodium object to the global namespace.

If a sodium object is already present in the global namespace, and the sodium.onload function is defined, this function will be called right after the library has been loaded and initialized.

<script>
window.sodium = { onload: function(sodium) {
  alert(sodium.to_hex(sodium.crypto_generichash(64, 'test')));
}};
</script> 
...
<script src="sodium.js" async defer></script>

As an alternative, use a module loader or Browserify as described below.

Usage with CommonJS/AMD/ES6 import

Copy the .js files for libsodium and libsodium-wrappers to your project and load the libsodium-wrappers module.

Alternatively, use yarn. The Yarn package is called libsodium-wrappers and includes a dependency on the raw libsodium module.

$ yarn add libsodium-wrappers
var sodium = require('libsodium-wrappers');
console.log(sodium.to_hex(sodium.crypto_generichash(64, 'test')));

List of wrapped algorithms and functions:

Additional helpers

  • from_hex(), to_hex()
  • from_string(), to_string()
  • memcmp() (constant-time check for equality, returns true or false)
  • compare() (constant-time comparison. Values must have the same size. Returns-1,0or1`)
  • memzero() (applies to Uint8Array objects)
  • increment() (increments an arbitrary-long number stored as a little-endian Uint8Array - typically to increment nonces)
  • add() (adds two arbitrary-long numbers stored as little-endian Uint8Array vectors)
  • is_zero() (constant-time, checks Uint8Array objects for all zeros)

API

The API exposed by the wrappers is identical to the one of the C library, except that buffer lengths never need to be explicitly given.

Binary input buffers should be Uint8Array objects. However, if a string is given instead, the wrappers will automatically convert the string to an array containing a UTF-8 representation of the string.

Example:

var key = sodium.randombytes_buf(sodium.crypto_shorthash_KEYBYTES),
    hash1 = sodium.crypto_shorthash(new Uint8Array([1, 2, 3, 4]), key),
    hash2 = sodium.crypto_shorthash('test', key);

If the output is a unique binary buffer, it is returned as a Uint8Array object.

However, an extra parameter can be given to all wrapped functions, in order to specify what format the output should be in. Valid options are `uint8array' (default), 'text' and 'hex'.

Example (shorthash):

var key = sodium.randombytes_buf(sodium.crypto_shorthash_KEYBYTES),
    hash_hex = sodium.crypto_shorthash('test', key, 'hex');

Example (secretbox):

// Load your secret key from a safe place and reuse it across multiple 
// secretbox calls. (Obviously don't use this example key for anything 
// real.) 
// 
var secret = Buffer.from('724b092810ec86d7e35c9d067702b31ef90bc43a7b598626749914d6a3e033ed', 'hex');
 
// Given a message as a string, return a Buffer containing the 
// nonce (in the first 24 bytes) and the encrypted content. 
var encrypt = function(message) {
    // You must use a different nonce for each message you encrypt. 
    var nonce = Buffer.from(sodium.randombytes_buf(sodium.crypto_box_NONCEBYTES));
    var buf = Buffer.from(message);
    return Buffer.concat([nonce, Buffer.from(sodium.crypto_secretbox_easy(buf, nonce, secret))]);
},
 
// Decrypt takes a Buffer and returns the decrypted message as plain text. 
var decrypt = function(encryptedBuffer) {
    var nonce = encryptedBuffer.slice(0, sodium.crypto_box_NONCEBYTES);
    var encryptedMessage = encryptedBuffer.slice(sodium.crypto_box_NONCEBYTES);
    return sodium.crypto_secretbox_open_easy(encryptedMessage, nonce, secret, 'text');
}

In addition, the from_hex, to_hex, from_string, and to_string functions are available to explicitly convert hexadecimal, and arbitrary string representations from/to Uint8Array objects.

Functions returning more than one output buffer are returning them as an object. For example, the sodium.crypto_box_keypair() function returns the following object:

{ keyType: 'curve25519', privateKey: (Uint8Array), publicKey: (Uint8Array) }

Standard vs Sumo version

The standard version (in the dist/browsers and dist/modules directories) contains the high-level functions, and is the recommended one for most projects.

Alternatively, the "sumo" version, available in the dist/browsers-sumo and dist/modules-sumo directories contains all the symbols from the original library. This includes undocumented, untested, deprecated, low-level and easy to misuse functions.

The crypto_pwhash_* function set is also only included in the Sumo version. The high amount of heap memory (allocated after loading) required by these functions may not be desirable when they are not being used.

The sumo version is slightly larger than the standard version, and should be used only if you really need the extra symbols it provides.

Compilation

If you want to compile the files yourself, the following dependencies need to be installed on your system:

  • autoconf
  • automake
  • emscripten
  • git
  • nodejs
  • libtool
  • make
  • zopfli (yarn global add node-zopfli)
  • uglifyjs (yarn global add uglify-js)

Running make will clone libsodium, build it, test it, build the wrapper, and create the modules and minified distribution files.

Custom build

The build available in this repository does not contain all the functions available in the original libsodium library.

Providing that you have all the build dependencies installed, here is how you can build libsodium.js to include the functions you need :

git clone https://github.com/jedisct1/libsodium.js
cd libsodium.js
 
# Get the original C version of libsodium and configure it 
make libsodium/configure
 
# Modify the emscripten.sh 
# Specifically, add the name of the missing functions and constants in the "EXPORTED_FUNCTIONS" array. 
# Ensure that the name begins with an underscore and that it is between double quotes. 
nano libsodium/dist-build/emscripten.sh
 
# Build libsodium, and then libsodium.js with your chosen functions 
make

NOTE: for each of the functions/constants you add, make sure that the corresponding symbol files exist in the wrapper/symbols folder and that the constants are listed in the wrapper/constants.json file.

Authors

Built by Ahmad Ben Mrad and Frank Denis.

License

This wrapper is distributed under the ISC License.