fernet

Fernet.js

Javascript implementation of Fernet symmetric encryption.

Fernet is an opinionated way of using AES and HMAC authentication that makes shared-secret symmetric encryption simpler for communicating applications.

Fernet.js combines Crypto-JS, sjcl, and browserify to provide a library that works in both node and the browser.

Instead of using TypedArrays I use Hex Strings and CryptoJS's Hex.parse to build up CryptoJs.lib.WordArray objects. The Stanford Javscript Crypto Library is used for pseudo-random number generation.

WARNING

It's generally never considered safe to encrypt data in the browser.

However, you can use this library to encrypt/decrypt data server-side and decrypt data on a client.

Use

node.js

var fernet = require('./fernet');

browser

<script src="fernetBrowser.js"></script>

Fernet

fernet.setSecret(string)

Sets the secret at the top level for all further Tokens made from this instance of Fernet.

fernet.ttl = seconds

Sets the ttl at the top level for all further Tokens made from this instance of Fernet.

Secret

Generating a secret

Generating appropriate secrets is beyond the scope of `Fernet`, but you should
generate it using `/dev/random` in a *nix. To generate a base64-encoded 256 bit
(32 byte) random sequence, try:

dd if=/dev/urandom bs=32 count=1 2>/dev/null | openssl base64

new fernet.Secret(string)

  var secret = new fernet.Secret("cw_0x689RpI-jtRR7oE8h_eQsKImvJapLeSbXpwF4e4=");
  /*
    {
      signingKeyHex: '730ff4c7af3d46923e8ed451ee813c87',
      signingKey: [CryptoJS.lib.WordArray],
      encryptionKeyHex: 'f790b0a226bc96a92de49b5e9c05e1ee',
      encryptionKey: [CryptoJS.lib.WordArray]
    }
  */

Token

new fernet.Token(options)

Options:

• secret: a fernet.Secret object
• token: a Fernet-encoded String
• ttl: seconds of ttl

For testing:

• time: Date object
• iv: Array of Integers

Token.prototype.encode

//Have to include time and iv to make it deterministic.
//Normally time would default to (new Date()) and iv to something random.
var token = new fernet.Token({
  secret: secret,
  time: Date.parse(1),
  iv: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
})
token.encode("Message")
/*
'gAAAAABSO_yhAAECAwQFBgcICQoLDA0OD1PGoFV6wgWZG6AOBfQqevwJT2qKtCZ0EjKy1_TvyxTseR_3ebIF6Ph-xa2QT_tEvg=='
*/

Token.prototype.decode

Include tt

var token = new fernet.Token({
  secret: secret,
  token: 'gAAAAABSO_yhAAECAwQFBgcICQoLDA0OD1PGoFV6wgWZG6AOBfQqevwJT2qKtCZ0EjKy1_TvyxTseR_3ebIF6Ph-xa2QT_tEvg==',
  ttl: 0
})
token.decode();

/*
"Message"
*/

Test

> npm test

Compiles new fernetBrowser.js via browserify, tests node lib with mocha, then opens test.html via open.