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encryptable_record.rb
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encryptable_record.rb
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# frozen_string_literal: true
module ActiveRecord
module Encryption
# This is the concern mixed in Active Record models to make them encryptable. It adds the +encrypts+
# attribute declaration, as well as the API to encrypt and decrypt records.
module EncryptableRecord
extend ActiveSupport::Concern
included do
class_attribute :encrypted_attributes
validate :cant_modify_encrypted_attributes_when_frozen, if: -> { has_encrypted_attributes? && ActiveRecord::Encryption.context.frozen_encryption? }
end
class_methods do
# Encrypts the +name+ attribute.
#
# === Options
#
# * <tt>:key_provider</tt> - A key provider to provide encryption and decryption keys. Defaults to
# +ActiveRecord::Encryption.key_provider+.
# * <tt>:key</tt> - A password to derive the key from. It's a shorthand for a +:key_provider+ that
# serves derivated keys. Both options can't be used at the same time.
# * <tt>:deterministic</tt> - By default, encryption is not deterministic. It will use a random
# initialization vector for each encryption operation. This means that encrypting the same content
# with the same key twice will generate different ciphertexts. When set to +true+, it will generate the
# initialization vector based on the encrypted content. This means that the same content will generate
# the same ciphertexts. This enables querying encrypted text with Active Record. Deterministic encryption
# will use the oldest encryption scheme to encrypt new data by default. You can change this by setting
# +deterministic: { fixed: false }+. That will make it use the newest encryption scheme for encrypting new
# data.
# * <tt>:downcase</tt> - When true, it converts the encrypted content to downcase automatically. This allows to
# effectively ignore case when querying data. Notice that the case is lost. Use +:ignore_case+ if you are interested
# in preserving it.
# * <tt>:ignore_case</tt> - When true, it behaves like +:downcase+ but, it also preserves the original case in a specially
# designated column +original_<name>+. When reading the encrypted content, the version with the original case is
# served. But you can still execute queries that will ignore the case. This option can only be used when +:deterministic+
# is true.
# * <tt>:context_properties</tt> - Additional properties that will override +Context+ settings when this attribute is
# encrypted and decrypted. E.g: +encryptor:+, +cipher:+, +message_serializer:+, etc.
# * <tt>:previous</tt> - List of previous encryption schemes. When provided, they will be used in order when trying to read
# the attribute. Each entry of the list can contain the properties supported by #encrypts. Also, when deterministic
# encryption is used, they will be used to generate additional ciphertexts to check in the queries.
def encrypts(*names, key_provider: nil, key: nil, deterministic: false, downcase: false, ignore_case: false, previous: [], **context_properties)
self.encrypted_attributes ||= Set.new # not using :default because the instance would be shared across classes
scheme = scheme_for key_provider: key_provider, key: key, deterministic: deterministic, downcase: downcase, \
ignore_case: ignore_case, previous: previous, **context_properties
names.each do |name|
encrypt_attribute name, scheme
end
end
# Returns the list of deterministic encryptable attributes in the model class.
def deterministic_encrypted_attributes
@deterministic_encrypted_attributes ||= encrypted_attributes&.find_all do |attribute_name|
type_for_attribute(attribute_name).deterministic?
end
end
# Given a attribute name, it returns the name of the source attribute when it's a preserved one.
def source_attribute_from_preserved_attribute(attribute_name)
attribute_name.to_s.sub(ORIGINAL_ATTRIBUTE_PREFIX, "") if /^#{ORIGINAL_ATTRIBUTE_PREFIX}/.match?(attribute_name)
end
private
def scheme_for(key_provider: nil, key: nil, deterministic: false, downcase: false, ignore_case: false, previous: [], **context_properties)
ActiveRecord::Encryption::Scheme.new(key_provider: key_provider, key: key, deterministic: deterministic,
downcase: downcase, ignore_case: ignore_case, **context_properties).tap do |scheme|
scheme.previous_schemes = global_previous_schemes_for(scheme) +
Array.wrap(previous).collect { |scheme_config| ActiveRecord::Encryption::Scheme.new(**scheme_config) }
end
end
def global_previous_schemes_for(scheme)
ActiveRecord::Encryption.config.previous_schemes.collect do |previous_scheme|
scheme.merge(previous_scheme)
end
end
def encrypt_attribute(name, attribute_scheme)
encrypted_attributes << name.to_sym
attribute name do |cast_type|
ActiveRecord::Encryption::EncryptedAttributeType.new scheme: attribute_scheme, cast_type: cast_type
end
preserve_original_encrypted(name) if attribute_scheme.ignore_case?
ActiveRecord::Encryption.encrypted_attribute_was_declared(self, name)
end
def preserve_original_encrypted(name)
original_attribute_name = "#{ORIGINAL_ATTRIBUTE_PREFIX}#{name}".to_sym
if !ActiveRecord::Encryption.config.support_unencrypted_data && !column_names.include?(original_attribute_name.to_s)
raise Errors::Configuration, "To use :ignore_case for '#{name}' you must create an additional column named '#{original_attribute_name}'"
end
encrypts original_attribute_name
override_accessors_to_preserve_original name, original_attribute_name
end
def override_accessors_to_preserve_original(name, original_attribute_name)
include(Module.new do
define_method name do
if ((value = super()) && encrypted_attribute?(name)) || !ActiveRecord::Encryption.config.support_unencrypted_data
send(original_attribute_name)
else
value
end
end
define_method "#{name}=" do |value|
self.send "#{original_attribute_name}=", value
super(value)
end
end)
end
def load_schema!
super
add_length_validation_for_encrypted_columns if ActiveRecord::Encryption.config.validate_column_size
end
def add_length_validation_for_encrypted_columns
encrypted_attributes&.each do |attribute_name|
validate_column_size attribute_name
end
end
def validate_column_size(attribute_name)
if limit = columns_hash[attribute_name.to_s]&.limit
validates_length_of attribute_name, maximum: limit
end
end
end
# Returns whether a given attribute is encrypted or not.
def encrypted_attribute?(attribute_name)
ActiveRecord::Encryption.encryptor.encrypted? ciphertext_for(attribute_name)
end
# Returns the ciphertext for +attribute_name+.
def ciphertext_for(attribute_name)
read_attribute_before_type_cast(attribute_name)
end
# Encrypts all the encryptable attributes and saves the changes.
def encrypt
encrypt_attributes if has_encrypted_attributes?
end
# Decrypts all the encryptable attributes and saves the changes.
def decrypt
decrypt_attributes if has_encrypted_attributes?
end
private
ORIGINAL_ATTRIBUTE_PREFIX = "original_"
def encrypt_attributes
validate_encryption_allowed
update_columns build_encrypt_attribute_assignments
end
def decrypt_attributes
validate_encryption_allowed
decrypt_attribute_assignments = build_decrypt_attribute_assignments
ActiveRecord::Encryption.without_encryption { update_columns decrypt_attribute_assignments }
end
def validate_encryption_allowed
raise ActiveRecord::Encryption::Errors::Configuration, "can't be modified because it is encrypted" if ActiveRecord::Encryption.context.frozen_encryption?
end
def has_encrypted_attributes?
self.class.encrypted_attributes.present?
end
def build_encrypt_attribute_assignments
Array(self.class.encrypted_attributes).index_with do |attribute_name|
self[attribute_name]
end
end
def build_decrypt_attribute_assignments
Array(self.class.encrypted_attributes).collect do |attribute_name|
type = type_for_attribute(attribute_name)
encrypted_value = ciphertext_for(attribute_name)
new_value = type.deserialize(encrypted_value)
[attribute_name, new_value]
end.to_h
end
def cant_modify_encrypted_attributes_when_frozen
self.class&.encrypted_attributes.each do |attribute|
errors.add(attribute.to_sym, "can't be modified because it is encrypted") if changed_attributes.include?(attribute)
end
end
end
end
end