ActiveSupport::MessageEncryptor
class ActiveSupport::MessageEncryptor
MessageEncryptor is a simple way to encrypt values which get stored somewhere you don't trust.
The cipher text and initialization vector are base64 encoded and returned to you.
This can be used in situations similar to the MessageVerifier
, but where you don't want users to be able to determine the value of the payload.
salt = SecureRandom.random_bytes(64) key = ActiveSupport::KeyGenerator.new('password').generate_key(salt, 32) # => "\x89\xE0\x156\xAC..." crypt = ActiveSupport::MessageEncryptor.new(key) # => #<ActiveSupport::MessageEncryptor ...> encrypted_data = crypt.encrypt_and_sign('my secret data') # => "NlFBTTMwOUV5UlA1QlNEN2xkY2d6eThYWWh..." crypt.decrypt_and_verify(encrypted_data) # => "my secret data"
Constants
- DEFAULT_CIPHER
- OpenSSLCipherError
Public Class Methods
Given a cipher, returns the key length of the cipher to help generate the key of desired size
# File activesupport/lib/active_support/message_encryptor.rb, line 88 def self.key_len(cipher = DEFAULT_CIPHER) OpenSSL::Cipher.new(cipher).key_len end
Initialize a new MessageEncryptor. secret
must be at least as long as the cipher key size. For the default 'aes-256-cbc' cipher, this is 256 bits. If you are using a user-entered secret, you can generate a suitable key by using ActiveSupport::KeyGenerator
or a similar key derivation function.
First additional parameter is used as the signature key for MessageVerifier
. This allows you to specify keys to encrypt and sign data.
ActiveSupport::MessageEncryptor.new('secret', 'signature_secret')
Options:
-
:cipher
- Cipher to use. Can be any cipher returned byOpenSSL::Cipher.ciphers
. Default is 'aes-256-cbc'. -
:digest
- String of digest to use for signing. Default isSHA1
. Ignored when using an AEAD cipher like 'aes-256-gcm'. -
:serializer
- Object serializer to use. Default isMarshal
.
# File activesupport/lib/active_support/message_encryptor.rb, line 64 def initialize(secret, *signature_key_or_options) options = signature_key_or_options.extract_options! sign_secret = signature_key_or_options.first @secret = secret @sign_secret = sign_secret @cipher = options[:cipher] || DEFAULT_CIPHER @digest = options[:digest] || "SHA1" unless aead_mode? @verifier = resolve_verifier @serializer = options[:serializer] || Marshal end
Public Instance Methods
Decrypt and verify a message. We need to verify the message in order to avoid padding attacks. Reference: www.limited-entropy.com/padding-oracle-attacks.
# File activesupport/lib/active_support/message_encryptor.rb, line 83 def decrypt_and_verify(value) _decrypt(verifier.verify(value)) end
Encrypt and sign a message. We need to sign the message in order to avoid padding attacks. Reference: www.limited-entropy.com/padding-oracle-attacks.
# File activesupport/lib/active_support/message_encryptor.rb, line 77 def encrypt_and_sign(value) verifier.generate(_encrypt(value)) end
© 2004–2017 David Heinemeier Hansson
Licensed under the MIT License.