= attr_encrypted {
}[https://travis-ci.org/attr-encrypted/attr_encrypted] {
}[https://codeclimate.com/github/attr-encrypted/attr_encrypted]{}[https://codeclimate.com/github/attr-encrypted/attr_encrypted]
Generates attr_accessors that encrypt and decrypt attributes transparently
It works with ANY class, however, you get a few extra features when you're using it with ActiveRecord, DataMapper, or Sequel
== Installation
gem install attr_encrypted
== Usage
=== Basic
Encrypting attributes has never been easier:
class User
attr_accessor :name
attr_encrypted :ssn, :key => 'a secret key'
def load
# loads the stored data
end
def save
# saves the :name and :encrypted_ssn attributes somewhere (e.g. filesystem, database, etc)
end
end
@user = User.new
@user.ssn = '123-45-6789'
@user.encrypted_ssn # returns the encrypted version of :ssn
@user.save
@user = User.load
@user.ssn # decrypts :encrypted_ssn and returns '123-45-6789'
The attr_encrypted method is also aliased as attr_encryptor to conform to Ruby's attr_ naming conventions. I should have called this project attr_encryptor but it was too late when I realized it ='(.
=== Adding required columns via database migration
By default, attr_encrypted uses the :single_iv_and_salt
encryption mode for compatibility with previous versions of the gem. This mode
uses a single IV and salt for each encrypted column. Create or modify your model
to add a column with the encrypted_ prefix (which can be modified, see
below), e.g. encrypted_ssn via a migration like the following:
create_table :users do |t|
t.string :name
t.string :encrypted_ssn
t.timestamps
end
For enhanced security, you can use the :per_attribute_iv_and_salt mode.
This requires additional _salt and _iv columns with the
encrypted_ prefix as follows and generates a unique salt and IV per
attribute:
create_table :users do |t|
t.string :name
t.string :encrypted_ssn
t.string :encrypted_ssn_salt
t.string :encrypted_ssn_iv
t.string :domain
t.timestamps
end
This mode is enabled by specifying a value of :per_attribute_iv_and_salt
via the :mode option as follows:
class User
attr_accessor :name
attr_encrypted :ssn, :key => 'a secret key', :mode => :per_attribute_iv_and_salt
end
Note that there are alternatives to storing the IV and salt in separate columns:
for example, see here[https://github.com/attr-encrypted/attr_encrypted/issues/118#issuecomment-45806629].
Note that migration from the old encryption scheme to the new is nontrivial. One
approach is described here[http://jjasonclark.com/switching_from_attr_encrypted_to_attr_encryptor],
though these instructions describe the now-defunct attr_encryptor gem
whose functionality has been merged into this project.
=== Specifying the encrypted attribute name
By default, the encrypted attribute name is encrypted_#{attribute} (e.g. attr_encrypted :email would create an attribute named encrypted_email). So, if you're storing the encrypted attribute in the database, you need to make sure the encrypted_#{attribute} field exists in your table. You have a couple of options if you want to name your attribute something else.
==== The :attribute option
You can simply pass the name of the encrypted attribute as the :attribute option:
class User
attr_encrypted :email, :key => 'a secret key', :attribute => 'email_encrypted'
end
This would generate an attribute named email_encrypted
==== The :prefix and :suffix options
If you're planning on encrypting a few different attributes and you don't like the encrypted_#{attribute} naming convention then you can specify your own:
class User
attr_encrypted :email, :credit_card, :ssn, :key => 'a secret key', :prefix => 'secret_', :suffix => '_crypted'
end
This would generate the following attributes: secret_email_crypted, secret_credit_card_crypted, and secret_ssn_crypted.
=== Encryption keys
Although a :key option may not be required (see custom encryptor below), it has a few special features
==== Unique keys for each attribute
You can specify unique keys for each attribute if you'd like:
class User
attr_encrypted :email, :key => 'a secret key'
attr_encrypted :ssn, :key => 'a different secret key'
end
==== Symbols representing instance methods as keys
If your class has an instance method that determines the encryption key to use, simply pass a symbol representing it like so:
class User
attr_encrypted :email, :key => :encryption_key
def encryption_key
# does some fancy logic and returns an encryption key
end
end
==== Procs as keys
You can pass a proc/lambda object as the :key option as well:
class User
attr_encrypted :email, :key => proc { |user| user.key }
end
This can be used to create asymmetrical encryption by requiring users to provide their own encryption keys.
=== Conditional encrypting
There may be times that you want to only encrypt when certain conditions are met. For example maybe you're using rails and you don't want to encrypt
attributes when you're in development mode. You can specify conditions like this:
class User < ActiveRecord::Base
attr_encrypted :email, :key => 'a secret key', :unless => Rails.env.development?
end
You can specify both :if and :unless options. If you pass a symbol representing an instance method then the result of the method will be evaluated. Any objects that respond to :call are evaluated as well.
=== Custom encryptor
The Encryptor (see http://github.com/shuber/encryptor) class is used by default. You may use your own custom encryptor by specifying
the :encryptor, :encrypt_method, and :decrypt_method options
Lets suppose you'd like to use this custom encryptor class:
class SillyEncryptor
def self.silly_encrypt(options)
(options[:value] + options[:secret_key]).reverse
end
def self.silly_decrypt(options)
options[:value].reverse.gsub(/#{options[:secret_key]}$/, '')
end
end
Simply set up your class like so:
class User
attr_encrypted :email, :secret_key => 'a secret key', :encryptor => SillyEncryptor, :encrypt_method => :silly_encrypt, :decrypt_method => :silly_decrypt
end
Any options that you pass to attr_encrypted will be passed to the encryptor along with the :value option which contains the string to encrypt/decrypt. Notice it uses :secret_key instead of :key.
=== Custom algorithms
The default Encryptor uses the standard ruby OpenSSL library. It's default algorithm is aes-256-cbc. You can modify this by passing the :algorithm option to the attr_encrypted call like so:
class User
attr_encrypted :email, :key => 'a secret key', :algorithm => 'bf'
end
Run openssl list-cipher-commands to view a list of algorithms supported on your platform. See http://github.com/shuber/encryptor for more information.
aes-128-cbc
aes-128-ecb
aes-192-cbc
aes-192-ecb
aes-256-cbc
aes-256-ecb
base64
bf
bf-cbc
bf-cfb
bf-ecb
bf-ofb
cast
cast-cbc
cast5-cbc
cast5-cfb
cast5-ecb
cast5-ofb
des
des-cbc
des-cfb
des-ecb
des-ede
des-ede-cbc
des-ede-cfb
des-ede-ofb
des-ede3
des-ede3-cbc
des-ede3-cfb
des-ede3-ofb
des-ofb
des3
desx
idea
idea-cbc
idea-cfb
idea-ecb
idea-ofb
rc2
rc2-40-cbc
rc2-64-cbc
rc2-cbc
rc2-cfb
rc2-ecb
rc2-ofb
rc4
rc4-40
=== Default options
Let's imagine that you have a few attributes that you want to encrypt with different keys, but you don't like the encrypted_#{attribute} naming convention. Instead of having to define your class like this:
class User
attr_encrypted :email, :key => 'a secret key', :prefix => '', :suffix => '_crypted'
attr_encrypted :ssn, :key => 'a different secret key', :prefix => '', :suffix => '_crypted'
attr_encrypted :credit_card, :key => 'another secret key', :prefix => '', :suffix => '_crypted'
end
You can simply define some default options like so:
class User
attr_encrypted_options.merge!(:prefix => '', :suffix => '_crypted')
attr_encrypted :email, :key => 'a secret key'
attr_encrypted :ssn, :key => 'a different secret key'
attr_encrypted :credit_card, :key => 'another secret key'
end
This should help keep your classes clean and DRY.
=== Encoding
You're probably going to be storing your encrypted attributes somehow (e.g. filesystem, database, etc) and may run into some issues trying to store a weird
encrypted string. I've had this problem myself using MySQL. You can simply pass the :encode option to automatically encode/decode when encrypting/decrypting.
class User
attr_encrypted :email, :key => 'some secret key', :encode => true
end
The default encoding is m* (base64). You can change this by setting :encode => 'some encoding'. See the Array#pack method at http://www.ruby-doc.org/core/classes/Array.html#M002245 for more encoding options.
=== Marshaling
You may want to encrypt objects other than strings (e.g. hashes, arrays, etc). If this is the case, simply pass the :marshal option to automatically marshal when encrypting/decrypting.
class User
attr_encrypted :credentials, :key => 'some secret key', :marshal => true
end
You may also optionally specify :marshaler, :dump_method, and :load_method if you want to use something other than the default Marshal object.
=== Encrypt/decrypt attribute methods
If you use the same key to encrypt every record (per attribute) like this:
class User
attr_encrypted :email, :key => 'a secret key'
end
Then you'll have these two class methods available for each attribute: User.encrypt_email(email_to_encrypt) and User.decrypt_email(email_to_decrypt). This can be useful when you're using ActiveRecord (see below).
=== ActiveRecord
If you're using this gem with ActiveRecord, you get a few extra features:
==== Default options
For your convenience, the :encode option is set to true by default since you'll be storing everything in a database.
==== Dynamic find_by_ and scoped_by_ methods
Let's say you'd like to encrypt your user's email addresses, but you also need a way for them to login. Simply set up your class like so:
class User < ActiveRecord::Base
attr_encrypted :email, :key => 'a secret key'
attr_encrypted :password, :key => 'some other secret key'
end
You can now lookup and login users like so:
User.find_by_email_and_password('test@example.com', 'testing')
The call to find_by_email_and_password is intercepted and modified to find_by_encrypted_email_and_encrypted_password('ENCRYPTED EMAIL', 'ENCRYPTED PASSWORD'). The dynamic scope methods like scoped_by_email_and_password work the same way.
NOTE: This only works if all records are encrypted with the same encryption key (per attribute).
=== DataMapper and Sequel
Just like the default options for ActiveRecord, the :encode option is set to true by default since you'll be storing everything in a database.
== Note on Patches/Pull Requests
* Fork the project.
* Make your feature addition or bug fix.
* Add tests for it. This is important so I don't break it in a
future version unintentionally.
* Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
* Send me a pull request. Bonus points for topic branches.