High-level authenticated encryption API used by Vault
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README.md

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Provides a high-level authenticated encryption API that Vault uses to encrypt its stored settings. It is not intended to be a long-term solution since eventually we will be able to use GCM mode or NaCl in Node, but for now I'm using a hand-rolled scheme based on the following:

  • The given key is used to derive an encryption key and a signing key using PBKDF2
  • A random iv is selected using crypto.randomBytes()
  • The plaintext is encrypted using AES-256-CBC with the encryption key and iv to produce ciphertext
  • iv and ciphertext are concatenated and signed using HMAC-SHA-256 with the signing key to produce mac
  • The result is the concatenation of iv, ciphertext and mac
+--------+      +--------+      +----------------+----------------+
| secret |----->| PBKDF2 |----->| encryption key |  signing key   |
+--------+      +--------+      +----------------+----------------+
                                    |                     |
+---------+                         V                     |
| message |------------------>+-------------+             |
+---------+     +----+        | AES-256-CBC |             |
                | iv |------->+-------------+             |
                +----+              |                     |
                   |                |                     |
                   V                V                     V
              +----------+------------------+     +--------------+
              |    iv    |    ciphertext    |---->| HMAC-SHA-256 |
              +----------+------------------+     +--------------+
                      |               |                 |
                      V               V                 V
                  +----------+------------------+-----------+
                  |    iv    |    ciphertext    |    mac    |
                  +----------+------------------+-----------+

Its high-level API provides a simple way to encrypt and decrypt text:

var Cipher = require('vault-cipher'),
    cipher = new Cipher('your secret key');

var ciphertext = cipher.encrypt('some text');

cipher.decrypt(ciphertext) // -> 'some text'

Settings

The cipher is configurable by passing options to the constructor, for example:

var cipher = new Cipher('secret key', {format: 'hex', work: 1000})

The available options are:

  • format: the output format of the ciphertext, either base64 (default) or hex
  • salt: a salt string used during PBKDF2 key derivation, defaults to a GUID embedded in the library
  • work: the number of PBKDF2 iterations used to derive the encryption and signing keys, default is 1000

License

(The MIT License)

Copyright (c) 2011-2015 James Coglan

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.