A library for storing encrypted data in Mongo using Mongoid. We looked at a few alternatives, but wanted something that stored the values securely and unobtrusively.

Mongoid 3 supports custom types that need to only provide a simple interface - allowing us to extend core Ruby types to secure any type while providing a clean interface for developers.

Queries encrypt data before searching the database, so equality matches work automatically.

• Ruby 1.9.3
• Mongoid 3.0
• "Bring your own" encryption, see below

gem 'mongoid-encrypted-fields'

• Configure the cipher to be used for encrypting field values:

  GibberishCipher can be found in examples - uses the Gibberish gem:

    Mongoid::EncryptedFields.cipher = GibberishCipher.new(ENV['MY_PASSWORD'], ENV['MY_SALT'])

• Use encrypted types for fields in your models:

  class Person
      include Mongoid::Document
  
      field :name, type: String
      field :ssn, type: Mongoid::EncryptedString
  end

• The field getter returns the unencrypted value:

  person = Person.new(ssn: '123456789')
  person.ssn # => '123456789'

• The encrypted value is accessible with the "encrypted" attribute

  person.ssn.encrypted # => <encrypted string>
  
  # It can also be accessed using the hash syntax supported by Mongoid
  person[:ssn] # => <encrypted string>

• Finding a model by an encrypted field works automatically (equality only):

  Person.where(ssn: '123456789').count() # ssn is encrypted before querying the database

• The Mongoid uniqueness validator is patched to detect of encrypted fields:

  class Person
      ...
      field :ssn, type: Mongoid::EncryptedString
      validates_uniqueness_of :ssn, case_sensitive: true # Works as expected
      validates_uniqueness_of :ssn, case_sensitive: false # Raises exception - encrypted field cannot support a case insensitive match
  end
  
  Person.create!(name: 'Bill', ssn: '123456789')
  Person.create!(name: 'Ted', ssn: '123456789') #=> fails with uniqueness error

• Single cipher for all encrypted fields
• Currently can encrypt these Mongoid types
  • Date
  • DateTime
  • Hash
  • String
  • Time
• The uniqueness validator for encrypted fields is always case-sensitive. Using it with case-sensitive false raises an exception.

(c) 2012 Koan Health. See LICENSE.txt for further details.