Module: Lockbox::Model

Defined in:: lib/lockbox/model.rb
Defined Under Namespace

Modules: Attached
Instance Method Summary collapse

#encrypts(*attributes, **options) ⇒ Object
Instance Method Details

#encrypts(*attributes, **options) ⇒ `Object`

Raises:
(ArgumentError)
# File 'lib/lockbox/model.rb', line 3

def encrypts(*attributes, **options)
  # support objects
  # case options[:type]
  # when Date
  #   options[:type] = :date
  # when Time
  #   options[:type] = :datetime
  # when JSON
  #   options[:type] = :json
  # when Hash
  #   options[:type] = :hash
  # when Array
  #   options[:type] = :array
  # when String
  #   options[:type] = :string
  # when Integer
  #   options[:type] = :integer
  # when Float
  #   options[:type] = :float
  # end

  custom_type = options[:type].respond_to?(:serialize) && options[:type].respond_to?(:deserialize)
  valid_types = [nil, :string, :boolean, :date, :datetime, :time, :integer, :float, :binary, :json, :hash, :array, :inet]
  raise ArgumentError, "Unknown type: #{options[:type]}" unless custom_type || valid_types.include?(options[:type])

  activerecord = defined?(ActiveRecord::Base) && self < ActiveRecord::Base
  raise ArgumentError, "Type not supported yet with Mongoid" if options[:type] && !activerecord

  raise ArgumentError, "No attributes specified" if attributes.empty?

  raise ArgumentError, "Cannot use key_attribute with multiple attributes" if options[:key_attribute] && attributes.size > 1

  original_options = options.dup

  attributes.each do |name|
    # per attribute options
    # TODO use a different name
    options = original_options.dup

    # add default options
    encrypted_attribute = options.delete(:encrypted_attribute) || "#{name}_ciphertext"

    # migrating
    original_name = name.to_sym
    name = "migrated_#{name}" if options[:migrating]

    name = name.to_sym

    options[:attribute] = name.to_s
    options[:encrypted_attribute] = encrypted_attribute
    options[:encode] = true unless options.key?(:encode)

    encrypt_method_name = "generate_#{encrypted_attribute}"
    decrypt_method_name = "decrypt_#{encrypted_attribute}"

    class_eval do
      # Lockbox uses custom inspect
      # but this could be useful for other gems
      if activerecord && ActiveRecord::VERSION::MAJOR >= 6
        # only add virtual attribute
        # need to use regexp since strings do partial matching
        # also, need to use += instead of <<
        self.filter_attributes += [/\A#{Regexp.escape(options[:attribute])}\z/]
      end

      @lockbox_attributes ||= {}

      if @lockbox_attributes.empty?
        def self.lockbox_attributes
          parent_attributes =
            if superclass.respond_to?(:lockbox_attributes)
              superclass.lockbox_attributes
            else
              {}
            end

          parent_attributes.merge(@lockbox_attributes || {})
        end

        # use same approach as activerecord serialization
        def serializable_hash(options = nil)
          options = options.try(:dup) || {}

          options[:except] = Array(options[:except])
          options[:except] += self.class.lockbox_attributes.flat_map { |_, v| [v[:attribute], v[:encrypted_attribute]] }

          super(options)
        end

        # maintain order
        # replace ciphertext attributes w/ virtual attributes (filtered)
        def inspect
          lockbox_attributes = {}
          lockbox_encrypted_attributes = {}
          self.class.lockbox_attributes.each do |_, lockbox_attribute|
            lockbox_attributes[lockbox_attribute[:attribute]] = true
            lockbox_encrypted_attributes[lockbox_attribute[:encrypted_attribute]] = lockbox_attribute[:attribute]
          end

          inspection = []
          # use serializable_hash like Devise
          values = serializable_hash
          self.class.attribute_names.each do |k|
            next if !has_attribute?(k) || lockbox_attributes[k]

            # check for lockbox attribute
            if lockbox_encrypted_attributes[k]
              # check if ciphertext attribute nil to avoid loading attribute
              v = send(k).nil? ? "nil" : "[FILTERED]"
              k = lockbox_encrypted_attributes[k]
            elsif values.key?(k)
              v = respond_to?(:attribute_for_inspect) ? attribute_for_inspect(k) : values[k].inspect

              # fix for https://github.com/rails/rails/issues/40725
              # TODO only apply to Active Record 6.0
              if respond_to?(:inspection_filter, true) && v != "nil"
                v = inspection_filter.filter_param(k, v)
              end
            else
              next
            end

            inspection << "#{k}: #{v}"
          end

          "#<#{self.class} #{inspection.join(", ")}>"
        end

        if activerecord
          # TODO wrap in module?
          def attributes
            # load attributes
            # essentially a no-op if already loaded
            # an exception is thrown if decryption fails
            self.class.lockbox_attributes.each do |_, lockbox_attribute|
              # don't try to decrypt if no decryption key given
              next if lockbox_attribute[:algorithm] == "hybrid" && lockbox_attribute[:decryption_key].nil?

              # it is possible that the encrypted attribute is not loaded, eg.
              # if the record was fetched partially (`User.select(:id).first`).
              # accessing a not loaded attribute raises an `ActiveModel::MissingAttributeError`.
              send(lockbox_attribute[:attribute]) if has_attribute?(lockbox_attribute[:encrypted_attribute])
            end
            super
          end

          # needed for in-place modifications
          # assigned attributes are encrypted on assignment
          # and then again here
          before_save do
            self.class.lockbox_attributes.each do |_, lockbox_attribute|
              attribute = lockbox_attribute[:attribute]

              if attribute_changed_in_place?(attribute)
                send("#{attribute}=", send(attribute))
              end
            end
          end

          def update_columns(attributes)
            return super unless attributes.is_a?(Hash)

            # transform keys like Active Record
            attributes = attributes.transform_keys do |key|
              n = key.to_s
              self.class.attribute_aliases[n] || n
            end

            lockbox_attributes = self.class.lockbox_attributes.slice(*attributes.keys.map(&:to_sym))
            return super unless lockbox_attributes.any?

            attributes_to_set = {}

            lockbox_attributes.each do |key, lockbox_attribute|
              attribute = key.to_s
              # check read only
              verify_readonly_attribute(attribute)

              message = attributes[attribute]
              attributes.delete(attribute) unless lockbox_attribute[:migrating]
              encrypted_attribute = lockbox_attribute[:encrypted_attribute]
              ciphertext = self.class.send("generate_#{encrypted_attribute}", message, context: self)
              attributes[encrypted_attribute] = ciphertext
              attributes_to_set[attribute] = message
              attributes_to_set[lockbox_attribute[:attribute]] = message if lockbox_attribute[:migrating]
            end

            result = super(attributes)

            # same logic as Active Record
            # (although this happens before saving)
            attributes_to_set.each do |k, v|
              if respond_to?(:write_attribute_without_type_cast, true)
                write_attribute_without_type_cast(k, v)
              elsif respond_to?(:raw_write_attribute, true)
                raw_write_attribute(k, v)
              else
                @attributes.write_cast_value(k, v)
                clear_attribute_change(k)
              end
            end

            result
          end
        else
          def reload
            self.class.lockbox_attributes.each do |_, v|
              instance_variable_set("@#{v[:attribute]}", nil)
            end
            super
          end
        end
      end

      raise "Duplicate encrypted attribute: #{original_name}" if lockbox_attributes[original_name]
      raise "Multiple encrypted attributes use the same column: #{encrypted_attribute}" if lockbox_attributes.any? { |_, v| v[:encrypted_attribute] == encrypted_attribute }
      @lockbox_attributes[original_name] = options

      if activerecord
        # preference:
        # 1. type option
        # 2. existing virtual attribute
        # 3. default to string (which can later be overridden)
        if options[:type]
          attribute_type =
            case options[:type]
            when :json, :hash, :array
              :string
            when :integer
              ActiveModel::Type::Integer.new(limit: 8)
            else
              options[:type]
            end

          attribute name, attribute_type

          serialize name, JSON if options[:type] == :json
          serialize name, Hash if options[:type] == :hash
          serialize name, Array if options[:type] == :array
        elsif !attributes_to_define_after_schema_loads.key?(name.to_s)
          # when migrating it's best to specify the type directly
          # however, we can try to use the original type if its already defined
          if attributes_to_define_after_schema_loads.key?(original_name.to_s)
            attribute name, attributes_to_define_after_schema_loads[original_name.to_s].first
          elsif options[:migrating]
            # we use the original attribute for serialization in the encrypt and decrypt methods
            # so we can use a generic value here
            attribute name, ActiveRecord::Type::Value.new
          else
            attribute name, :string
          end
        else
          # hack for Active Record 6.1
          # to set string type after serialize
          # otherwise, type gets set to ActiveModel::Type::Value
          # which always returns false for changed_in_place?
          # earlier versions of Active Record take the previous code path
          if ActiveRecord::VERSION::STRING.to_f >= 7.0 && attributes_to_define_after_schema_loads[name.to_s].first.is_a?(Proc)
            attribute_type = attributes_to_define_after_schema_loads[name.to_s].first.call(nil)
            if attribute_type.is_a?(ActiveRecord::Type::Serialized) && attribute_type.subtype.nil?
              attribute name, ActiveRecord::Type::Serialized.new(ActiveRecord::Type::String.new, attribute_type.coder)
            end
          elsif ActiveRecord::VERSION::STRING.to_f >= 6.1 && attributes_to_define_after_schema_loads[name.to_s].first.is_a?(Proc)
            attribute_type = attributes_to_define_after_schema_loads[name.to_s].first.call
            if attribute_type.is_a?(ActiveRecord::Type::Serialized) && attribute_type.subtype.nil?
              attribute name, ActiveRecord::Type::Serialized.new(ActiveRecord::Type::String.new, attribute_type.coder)
            end
          end
        end

        define_method("#{name}_was") do
          send(name) # writes attribute when not already set
          super()
        end

        # restore ciphertext as well
        define_method("restore_#{name}!") do
          super()
          send("restore_#{encrypted_attribute}!")
        end

        if ActiveRecord::VERSION::STRING >= "5.1"
          define_method("#{name}_in_database") do
            send(name) # writes attribute when not already set
            super()
          end
        end
      else
        # keep this module dead simple
        # Mongoid uses changed_attributes to calculate keys to update
        # so we shouldn't mess with it
        m = Module.new do
          define_method("#{name}=") do |val|
            instance_variable_set("@#{name}", val)
          end

          define_method(name) do
            instance_variable_get("@#{name}")
          end
        end

        include m

        alias_method "#{name}_changed?", "#{encrypted_attribute}_changed?"

        define_method "#{name}_was" do
          ciphertext = send("#{encrypted_attribute}_was")
          self.class.send(decrypt_method_name, ciphertext, context: self)
        end

        define_method "#{name}_change" do
          ciphertexts = send("#{encrypted_attribute}_change")
          ciphertexts.map { |v| self.class.send(decrypt_method_name, v, context: self) } if ciphertexts
        end

        define_method "reset_#{name}!" do
          instance_variable_set("@#{name}", nil)
          send("reset_#{encrypted_attribute}!")
          send(name)
        end

        define_method "reset_#{name}_to_default!" do
          instance_variable_set("@#{name}", nil)
          send("reset_#{encrypted_attribute}_to_default!")
          send(name)
        end
      end

      define_method("#{name}?") do
        send("#{encrypted_attribute}?")
      end

      define_method("#{name}=") do |message|
        # decrypt first for dirty tracking
        # don't raise error if can't decrypt previous
        # don't try to decrypt if no decryption key given
        unless options[:algorithm] == "hybrid" && options[:decryption_key].nil?
          begin
            send(name)
          rescue Lockbox::DecryptionError
            warn "[lockbox] Decrypting previous value failed"
          end
        end

        send("lockbox_direct_#{name}=", message)

        # warn every time, as this should be addressed
        # maybe throw an error in the future
        if !options[:migrating]
          if activerecord
            if self.class.columns_hash.key?(name.to_s)
              warn "[lockbox] WARNING: Unencrypted column with same name: #{name}. Set `ignored_columns` or remove it to protect the data."
            end
          else
            if self.class.fields.key?(name.to_s)
              warn "[lockbox] WARNING: Unencrypted field with same name: #{name}. Remove it to protect the data."
            end
          end
        end

        super(message)
      end

      # separate method for setting directly
      # used to skip blind indexes for key rotation
      define_method("lockbox_direct_#{name}=") do |message|
        ciphertext = self.class.send(encrypt_method_name, message, context: self)
        send("#{encrypted_attribute}=", ciphertext)
      end
      private :"lockbox_direct_#{name}="

      define_method(name) do
        message = super()

        # possibly keep track of decrypted attributes directly in the future
        # Hash serializer returns {} when nil, Array serializer returns [] when nil
        # check for this explicitly as a layer of safety
        if message.nil? || ((message == {} || message == []) && activerecord && @attributes[name.to_s].value_before_type_cast.nil?)
          ciphertext = send(encrypted_attribute)

          # keep original message for empty hashes and arrays
          unless ciphertext.nil?
            message = self.class.send(decrypt_method_name, ciphertext, context: self)
          end

          if activerecord
            # set previous attribute so changes populate correctly
            # it's fine if this is set on future decryptions (as is the case when message is nil)
            # as only the first value is loaded into changes
            @attributes[name.to_s].instance_variable_set("@value_before_type_cast", message)

            # cache
            # decrypt method does type casting
            if respond_to?(:write_attribute_without_type_cast, true)
              write_attribute_without_type_cast(name.to_s, message) if !@attributes.frozen?
            elsif respond_to?(:raw_write_attribute, true)
              raw_write_attribute(name, message) if !@attributes.frozen?
            else
              if !@attributes.frozen?
                @attributes.write_cast_value(name.to_s, message)
                clear_attribute_change(name)
              end
            end
          else
            instance_variable_set("@#{name}", message)
          end
        end

        message
      end

      # for fixtures
      define_singleton_method encrypt_method_name do |message, **opts|
        table = activerecord ? table_name : collection_name.to_s

        unless message.nil?
          # TODO use attribute type class in 0.7.0
          case options[:type]
          when :boolean
            message = ActiveRecord::Type::Boolean.new.serialize(message)
            message = nil if message == "" # for Active Record < 5.2
            message = message ? "t" : "f" unless message.nil?
          when :date
            message = ActiveRecord::Type::Date.new.serialize(message)
            # strftime should be more stable than to_s(:db)
            message = message.strftime("%Y-%m-%d") unless message.nil?
          when :datetime
            message = ActiveRecord::Type::DateTime.new.serialize(message)
            message = nil unless message.respond_to?(:iso8601) # for Active Record < 5.2
            message = message.iso8601(9) unless message.nil?
          when :time
            message = ActiveRecord::Type::Time.new.serialize(message)
            message = nil unless message.respond_to?(:strftime)
            message = message.strftime("%H:%M:%S.%N") unless message.nil?
            message
          when :integer
            message = ActiveRecord::Type::Integer.new(limit: 8).serialize(message)
            message = 0 if message.nil?
            # signed 64-bit integer, big endian
            message = [message].pack("q>")
          when :float
            message = ActiveRecord::Type::Float.new.serialize(message)
            # double precision, big endian
            message = [message].pack("G") unless message.nil?
          when :inet
            unless message.nil?
              ip = message.is_a?(IPAddr) ? message : (IPAddr.new(message) rescue nil)
              # same format as Postgres, with ipv4 padded to 16 bytes
              # family, netmask, ip
              # return nil for invalid IP like Active Record
              message = ip ? [ip.ipv4? ? 0 : 1, ip.prefix, ip.hton].pack("CCa16") : nil
            end
          when :string, :binary
            # do nothing
            # encrypt will convert to binary
          else
            # use original name for serialized attributes
            type = (try(:attribute_types) || {})[original_name.to_s]
            message = type.serialize(message) if type
          end
        end

        if message.nil? || (message == "" && !options[:padding])
          message
        else
          Lockbox::Utils.build_box(opts[:context], options, table, encrypted_attribute).encrypt(message)
        end
      end

      define_singleton_method decrypt_method_name do |ciphertext, **opts|
        message =
          if ciphertext.nil? || (ciphertext == "" && !options[:padding])
            ciphertext
          else
            table = activerecord ? table_name : collection_name.to_s
            Lockbox::Utils.build_box(opts[:context], options, table, encrypted_attribute).decrypt(ciphertext)
          end

        unless message.nil?
          # TODO use attribute type class in 0.7.0
          case options[:type]
          when :boolean
            message = message == "t"
          when :date
            message = ActiveRecord::Type::Date.new.deserialize(message)
          when :datetime
            message = ActiveRecord::Type::DateTime.new.deserialize(message)
          when :time
            message = ActiveRecord::Type::Time.new.deserialize(message)
          when :integer
            message = ActiveRecord::Type::Integer.new(limit: 8).deserialize(message.unpack("q>").first)
          when :float
            message = ActiveRecord::Type::Float.new.deserialize(message.unpack("G").first)
          when :string
            message.force_encoding(Encoding::UTF_8)
          when :binary
            # do nothing
            # decrypt returns binary string
          when :inet
            family, prefix, addr = message.unpack("CCa16")
            len = family == 0 ? 4 : 16
            message = IPAddr.new_ntoh(addr.first(len))
            message.prefix = prefix
          else
            # use original name for serialized attributes
            type = (try(:attribute_types) || {})[original_name.to_s]
            message = type.deserialize(message) if type
            message.force_encoding(Encoding::UTF_8) if !type || type.is_a?(ActiveModel::Type::String)
          end
        end

        message
      end

      if options[:migrating]
        # TODO reuse module
        m = Module.new do
          define_method "#{original_name}=" do |value|
            result = super(value)
            send("#{name}=", send(original_name))
            result
          end

          unless activerecord
            define_method "reset_#{original_name}!" do
              result = super()
              send("#{name}=", send(original_name))
              result
            end
          end
        end
        prepend m
      end
    end
  end
end
Module: Lockbox::Model

Defined Under Namespace

Instance Method Summary collapse

Instance Method Details

#encrypts(*attributes, **options) ⇒ Object

#encrypts(*attributes, **options) ⇒ `Object`
