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 133 Kb (minified, gzipped) and can run in a web browser as well as server-side.

Installation

Ready-to-use files based on libsodium 1.0.2 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.

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>

Usage with AMD or RequireJS

Copy the .js files for libsodium and sodium to your project and load the sodium module:

var sodium = require('sodium');
console.log(sodium.to_hex(sodium.crypto_generichash(64, 'test')));

List of wrapped algorithms and functions:

• crypto_aead (ChaCha20-Poly1305)
• crypto_auth (SHA256, SHA512, and the default crypto_auth with SHA512/256)
• crypto_box
• crypto_generichash (Blake2b)
• crypto_hash (SHA512/256)
• crypto_pwhash (scrypt)
• crypto_scalarmult (Curve25519)
• crypto_secretbox
• crypto_shorthash (SipHash)
• crypto_sign (Ed25519)
• Ed25519->Curve25519 conversion
• randombytes

Additional helpers

• from_base64(), to_base64()
• from_hex(), to_hex()
• memcmp() (constant-time comparison, returns true or false)
• memzero() (applies to Uint8Array objects)

API

The API exposed by the wrappers is identical to the one of the C library, except that buffer lengths never need to be explicitely 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', 'hex' and 'base64'.

Example:

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

In addition, the from_base64, to_base64, from_hex and to_hex functions are available to explicitly convert base64 and hexadecimal 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) }

Compilation

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

• autoconf
• automake
• emscripten
• git
• io.js or nodejs
• libtool
• make
• zopfli

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

Authors

Built by Ahmad Ben Mrad and Frank Denis.

License

This wrapper is distributed under the ISC License.