blob: 7773611e110744852d37b1a43227110e1c51a7de (
plain) (
blame)
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
|
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
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>: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, :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
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::Cipher.new(@cipher)
end
def verifier
@verifier
end
end
end
|
