View Source Cloak

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Cloak is an Elixir encryption library that implements several best practices and conveniences for Elixir developers:

  • Random IVs
  • Tagged ciphertexts
  • Elixir-native configuration

Documentation

Examples

Encrypt / Decrypt 

{:ok, ciphertext} = MyApp.Vault.encrypt("plaintext")
# => {:ok, <<1, 10, 65, 69, 83, 46, 71, 67, 77, 46, 86, 49, 45, 1, 250, 221,
# =>  189, 64, 26, 214, 26, 147, 171, 101, 181, 158, 224, 117, 10, 254, 140, 207,
# =>  215, 98, 208, 208, 174, 162, 33, 197, 179, 56, 236, 71, 81, 67, 85, 229,
# =>  ...>>}

MyApp.Vault.decrypt(ciphertext)
# => {:ok, "plaintext"}

Reencrypt With New Algorithm/Key 

"plaintext"
|> MyApp.Vault.encrypt!(:aes_256)
|> MyApp.Vault.decrypt!()
|> MyApp.Vault.encrypt!(:aes_256)
|> MyApp.Vault.decrypt!()
# => "plaintext"

Configuration 

config :my_app, MyApp.Vault,
  ciphers: [
    # In AES.GCM, it is important to specify 12-byte IV length for
    # interoperability with other encryption software. See this GitHub issue
    # for more details: https://github.com/danielberkompas/cloak/issues/93
    #
    # In Cloak 2.0, this will be the default iv length for AES.GCM.
    aes_gcm: {Cloak.Ciphers.AES.GCM, tag: "AES.GCM.V1", key: <<...>>, iv_length: 12},
    aes_ctr: {Cloak.Ciphers.AES.CTR, tag: "AES.CTR.V1", key: <<...>>}
  ]

Features

Random Initialization Vectors (IV)

Every strong encryption algorithm recommends unique initialization vectors. Cloak automatically generates unique vectors using :crypto.strong_rand_bytes, and includes the IV in the ciphertext. This greatly simplifies storage and is not a security risk.

Tagged Ciphertext

Each ciphertext contains metadata about the algorithm and key which was used to encrypt it. This allows Cloak to automatically select the correct key and algorithm to use for decryption for any given ciphertext.

This makes key rotation much easier, because you can easily tell whether any given ciphertext is using the old key or the new key.

Elixir-Native Configuration

Cloak works through Vault modules which you define in your app, and add to your supervision tree.

You can have as many vaults as you wish running simultaneously in your project. (This works well with umbrella apps, or any runtime environment where you have multiple OTP apps using Cloak)

Ecto Support

You can use Cloak to transparently encrypt Ecto fields, using cloak_ecto.

Security Notes

  • Cloak is built on Erlang's crypto library, and therefore inherits its security.
  • You can implement your own cipher modules to use with Cloak, which may use any other encryption algorithms of your choice.

Copyright (c) 2015 Daniel Berkompas

This work is free. You can redistribute it and/or modify it under the terms of the MIT License. See the LICENSE.md file for more details.