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) # => "\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"
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 with OpenSSL::Digest::SHA256.new(user_secret).digest
or similar.
Options:
:cipher
- Cipher to use. Can be any cipher returned by OpenSSL::Cipher.ciphers
. Default is 'aes-256-cbc'.
:serializer
- Object serializer to use. Default is Marshal
.
# File activesupport/lib/active_support/message_encryptor.rb, line 44 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, :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 62 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 56 def encrypt_and_sign(value) verifier.generate(_encrypt(value)) end
© 2004–2016 David Heinemeier Hansson
Licensed under the MIT License.