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"
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 70 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.
Options:
:cipher
- Cipher to use. Can be any cipher returned by OpenSSL::Cipher.ciphers
. Default is 'aes-256-cbc'.
:digest
- String of digest to use for signing. Default is SHA1
.
:serializer
- Object serializer to use. Default is Marshal
.
# File activesupport/lib/active_support/message_encryptor.rb, line 47 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] || 'aes-256-cbc' @verifier = MessageVerifier.new(@sign_secret || @secret, digest: options[:digest] || 'SHA1', serializer: NullSerializer) @serializer = options[:serializer] || Marshal end
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 65 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 59 def encrypt_and_sign(value) verifier.generate(_encrypt(value)) end
© 2004–2017 David Heinemeier Hansson
Licensed under the MIT License.