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 attr_encrypted
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 know that I should have called this project attr_encryptor but it was too late when I realized it =‘(.
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.
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| user.key } end
This can be used to create asymmetrical encryption by requiring users to provide their own encryption keys.
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 Encryptor (see 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.
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 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 the Array#pack method at www.ruby-doc.org/core/classes/Array.html#M002245 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('[email protected]', '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.
When you define an encrypted attribute for DataMapper, your definition needs to follow the underlying encrypted property’s definition. For example,
property encrypted_secret_key, String, :required => true, length => 100 attr_encrypted secret_key, :key => 'my key for keys'
Doing it in the opposite order will not work at all.
Also, it should go without saying that attributes that are not defined as properties are not persisted. The following model contains only one column:
class NoImplicitProperties include DataMapper::Resource property id, Serial attr_encrypted email, :key => 'my key for keys' end
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Fork the project.
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Make your feature addition or bug fix.
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Add tests for it. This is important so I don’t break it in a future version unintentionally.
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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)
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Send me a pull request. Bonus points for topic branches.
Problems, comments, and suggestions all welcome: [email protected]