View Source Cloak.Ecto

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Easily encrypt fields in your Ecto schemas. Relies on Cloak for encryption.


Cloak.Ecto helps you create Ecto.Type modules which automatically encrypt and decrypt your data. You simply define a type and set the type of your fields, and Cloak.Ecto handles the rest.

defmodule MyApp.Encrypted.Binary do
  use Cloak.Ecto.Binary, vault: MyApp.Vault
defmodule MyApp.EctoSchema do
  use Ecto.Schema

  schema "table_name" do
    field :encrypted_field, MyApp.Encrypted.Binary

    # ...

When Ecto writes the fields to the database, Cloak encrypts the values into a binary blob, using a configured encryption algorithm chosen by you.

iex> Repo.insert!(%MyApp.EctoSchema{encrypted_field: "plaintext"})
08:46:08.862 [debug] QUERY OK db=3.4ms
INSERT INTO "table_name" ("encrypted_field") 
VALUES ($1) RETURNING "id", "encrypted_field" [
  <<1,10, 65, 69, 83, 46, 67, 84, 82, 46, 86, 49, 
    69, 92, 173, 219, 203, 238, 26, 58, 236, 5, 
    104, 23, 12, 10, 182, 31, 221, 89, 22, 58, 
    34, 79, 109, 30, 70, 254, 56, 93, 102, 84>>

Likewise, when Ecto reads the encrypted blob out of the database, Cloak will automatically decrypt the value into the intended data type at runtime.

iex> Repo.get(MyApp.EctoSchema, 1)
%MyApp.EctoSchema{encrypted_field: "plaintext"}

For complete usage instructions, see the Hex documentation.


See our troubleshooting guide for solutions to common issues.

Notable Features

  • Transparent, easy to use encryption for database fields
  • Fully compatible with umbrella projects
  • Bring your own encryption algorithm, if you want
  • Mix task for key rotation: mix cloak.migrate

Security Notes

  • Supported Algorithms: Cloak's built-in encryption modules rely on Erlang's :crypto module. Cloak supports the following algorithms out of the box:

    • AES.GCM
    • AES.CTR
  • Encrypted Data Not Searchable: Cloak uses random IVs for each ciphertext. This means that the same value will not encrypt to the same value twice. As a result, encrypted columns are not queryable. However, Cloak does provide easy ways to create hashed, searchable columns.

  • Runtime Data is not Encrypted: Cloak encrypts data at rest in the database. The data in your Ecto structs at runtime is not encrypted.

  • No Support for User-specific Encryption Keys: Cloak's Ecto.Type modules do not support user-specific encryption keys, due to limitations on the Ecto.Type behaviour. However, you can still use Cloak's ciphers to implement these in your application logic.

Use Without Ecto

If you want to use Cloak without Ecto, see cloak instead.

Local Development

To develop this library locally, you will need to install the correct version of Elixir and Postgres. The easiest way to set everything up is with Docker and docker-compose:

$ cd cloak_ecto
# Runs the bin/test script in the context of Docker
$ docker-compose run code bin/test
# To access a terminal with mix, use this command:
$ docker-compose run code bash
# Run any command of your choosing:
root@234098234oij:/app# mix docs