/usr/lib/ruby/vendor_ruby/active_support/message_encryptor.rb is in ruby-activesupport 2:4.2.10-0ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | require 'openssl'
require 'base64'
require 'active_support/core_ext/array/extract_options'
module ActiveSupport
# 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 <tt>MessageVerifier</tt>, 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"
class MessageEncryptor
DEFAULT_CIPHER = "aes-256-cbc"
module NullSerializer #:nodoc:
def self.load(value)
value
end
def self.dump(value)
value
end
end
class InvalidMessage < StandardError; end
OpenSSLCipherError = OpenSSL::Cipher::CipherError
# 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 <tt>OpenSSL::Digest::SHA256.new(user_secret).digest</tt> or
# similar.
#
# Options:
# * <tt>:cipher</tt> - Cipher to use. Can be any cipher returned by
# <tt>OpenSSL::Cipher.ciphers</tt>. Default is 'aes-256-cbc'.
# * <tt>:digest</tt> - String of digest to use for signing. Default is +SHA1+.
# * <tt>:serializer</tt> - Object serializer to use. Default is +Marshal+.
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
# Encrypt and sign a message. We need to sign the message in order to avoid
# padding attacks. Reference: http://www.limited-entropy.com/padding-oracle-attacks.
def encrypt_and_sign(value)
verifier.generate(_encrypt(value))
end
# Decrypt and verify a message. We need to verify the message in order to
# avoid padding attacks. Reference: http://www.limited-entropy.com/padding-oracle-attacks.
def decrypt_and_verify(value)
_decrypt(verifier.verify(value))
end
# Given a cipher, returns the key length of the cipher to help generate the key of desired size
def self.key_len(cipher = DEFAULT_CIPHER)
OpenSSL::Cipher.new(cipher).key_len
end
private
def _encrypt(value)
cipher = new_cipher
cipher.encrypt
cipher.key = @secret
# Rely on OpenSSL for the initialization vector
iv = cipher.random_iv
encrypted_data = cipher.update(@serializer.dump(value))
encrypted_data << cipher.final
"#{::Base64.strict_encode64 encrypted_data}--#{::Base64.strict_encode64 iv}"
end
def _decrypt(encrypted_message)
cipher = new_cipher
encrypted_data, iv = encrypted_message.split("--").map {|v| ::Base64.strict_decode64(v)}
cipher.decrypt
cipher.key = @secret
cipher.iv = iv
decrypted_data = cipher.update(encrypted_data)
decrypted_data << cipher.final
@serializer.load(decrypted_data)
rescue OpenSSLCipherError, TypeError, ArgumentError
raise InvalidMessage
end
def new_cipher
OpenSSL::Cipher.new(@cipher)
end
def verifier
@verifier
end
end
end
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