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
gem install shuber-attr_encrypted --source http://gems.github.com
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'
By default, the encrypted attribute name is encrypted_#{attribute} (e.g. attr_encrypted :email would create an attribute named encrypted_email).
You have a couple of options if you want to name your attribute something else.
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
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.
Although a :key option may not be required (see custom encryptor below), it has a few special features
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
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
You can pass a proc/lambda object as the :key option as well:
class User
attr_encrypted :email, :key => proc { |user| ... }
end
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.
The Huberry::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.
The default Huberry::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
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.
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 Array#pack for more encoding options.
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
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).
If you're using this gem with ActiveRecord, you get a few extra features:
For your convenience, the :encode option is set to true by default since you'll be storing everything in a database.
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).
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.
Problems, comments, and suggestions all welcome: shuber@huberry.com