Introduction

ActsAsSecure adds an ability to store ActiveRecord model’s fields encrypted in a DB. When a model is marked with acts_as_secure, the :binary type fields are recognized as needed to be stored encrypted. The plugin does before_save/after_save/after_find encryption/decryption thus making it transparent for a code using the secure models.

The plugin supports a master key approach as well as individual records encryption keys. It does not contain any crypto provider but allows to plug in any external one as long as it supports encrypt/decrypt methods.

The fields are converted to a YAML form before encryption. After description they are restored via YAML.load. Since fields are stored encrypted, the find usage is very limited.

Compatibility

This is only compatible with Rails 3.

Installation

As gem, add the following to your gemfile.

gem 'jcnnghm-acts_as_secure'

Usage

Master Key Provider Usage

class SecureModel < ActiveRecord::Base
  acts_as_secure :crypto_provider => MasterKeyProviderClassOrInstance
end
SecureModel.create()
SecureModel.find(:first)

Individual Keys Provider Usage

class SecureModel < ActiveRecord::Base
  acts_as_secure
end
SecureModel.with_crypto_provider(SomeProvider.new(some_param)) { SecureModel.find(:first) }
SecureModel.with_crypto_provider(SomeProvider.new(some_param)) { SecureModel.create() }

Other Options

acts_as_secure :storage_type => :text  -- changes the secure storage type from :binary to the supplied one
acts_as_secure :except => [:field1, :field2] -- disables the secure behavior for the :binary type fields in a supplied list

Example

Let’s define three models: Fruit (not secure), SecretFruit (uses the master key approach), and UberSecretFruit (uses the individual key approach).

Rot13CryptoProvider represents a master key provider. SaltedRot13CryptoProvider depends on a salt individual for each record.

Models

class Fruit < ActiveRecord::Base
  has_one :secret_fruit
  has_one :uber_secret_fruit
end
class CreateFruits < ActiveRecord::Migration
  def self.up
    create_table :fruits do |t|
      t.column :name, :string
    end
  end
end
class Rot13CryptoProvider
  class << self
    def encrypt(arg)
      arg.tr("A-Za-z", "N-ZA-Mn-za-m")
    end
    alias_method :decrypt, :encrypt
  end
end
class SecretFruit < ActiveRecord::Base
  acts_as_secure :crypto_provider => Rot13CryptoProvider
  belongs_to :fruit
end
class CreateSecretFruits < ActiveRecord::Migration
  def self.up
    create_table :secret_fruits do |t|
      t.column :name, :binary
      t.column :fruit_id, :integer
    end
  end
end
class SaltedRot13CryptoProvider
  def initialize(salt)
    @salt = salt
  end
  def encrypt(arg)
    @salt + arg.tr("A-Za-z", "N-ZA-Mn-za-m")
  end
  def decrypt(arg)
    arg[@salt.size .. -1].tr("A-Za-z", "N-ZA-Mn-za-m")
  end
end
class UberSecretFruit < ActiveRecord::Base
  acts_as_secure
  belongs_to :fruit
end
class CreateUberSecretFruits < ActiveRecord::Migration
  def self.up
    create_table :uber_secret_fruits do |t|
      t.column :name, :binary
      t.column :fruit_id, :integer
    end
  end
end

Usage

>> f = Fruit.create(:name => 'passion fruit')
>> SecretFruit.create(:name => 'maracuya', :fruit => f)
>> puts f.secret_fruit.name
maracuya
>> secret = readline.chomp
uber_secret
>> crypto_provider = SaltedRot13CryptoProvider.new(secret)
>> UberSecretFruit.with_crypto_provider(crypto_provider) { UberSecretFruit.create(:name => 'Passiflora edulis', :fruit => f) }
>> UberSecretFruit.with_crypto_provider(crypto_provider) { puts f.uber_secret_fruit.name }
Passiflora edulis

DB

> select * from secret_fruits;
+----+---------------+----------+
| id | name          | fruit_id |
+----+---------------+----------+
|  1 | --- znenphln  |        1 |
+----+---------------+----------+
> select * from uber_secret_fruits;
+----+-----------------------------------+----------+
| id | name                              | fruit_id |
+----+-----------------------------------+----------+
|  1 | uber_secret--- Cnffvsyben rqhyvf  |        1 |
+----+-----------------------------------+----------+

Running Tests

bundle exec rspec spec

License

ActsAsSecure released under the MIT license.