Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Browse files

Add ActiveSupport::KeyGenerator as a simple wrapper around PBKDF2

This will be used to derive keys from the secret and a salt, in order to allow us to
do things like encrypted cookie stores without using the secret for multiple
purposes directly.
  • Loading branch information...
commit def2ccb8e3534e06ec1bb9c33aeee35a52b40138 1 parent a6cfd33
@NZKoz authored
View
1  activesupport/lib/active_support.rb
@@ -48,6 +48,7 @@ module ActiveSupport
autoload :Gzip
autoload :Inflector
autoload :JSON
+ autoload :KeyGenerator
autoload :MessageEncryptor
autoload :MessageVerifier
autoload :Multibyte
View
23 activesupport/lib/active_support/key_generator.rb
@@ -0,0 +1,23 @@
+require 'openssl'
+
+module ActiveSupport
+ # KeyGenerator is a simple wrapper around OpenSSL's implementation of PBKDF2
+ # It can be used to derive a number of keys for various purposes from a given secret.
+ # This lets rails applications have a single secure secret, but avoid reusing that
+ # key in multiple incompatible contexts.
+ class KeyGenerator
+ def initialize(secret, options = {})
+ @secret = secret
+ # The default iterations are higher than required for our key derivation uses
+ # on the off chance someone uses this for password storage
+ @iterations = options[:iterations] || 2**16
+ end
+
+ # Returns a derived key suitable for use. The default key_size is chosen
+ # to be compatible with the default settings of ActiveSupport::MessageVerifier.
+ # i.e. OpenSSL::Digest::SHA1#block_length
+ def generate_key(salt, key_size=64)
+ OpenSSL::PKCS5.pbkdf2_hmac_sha1(@secret, salt, @iterations, key_size)
+ end
+ end
+end
View
32 activesupport/test/key_generator_test.rb
@@ -0,0 +1,32 @@
+require 'abstract_unit'
+
+begin
+ require 'openssl'
+ OpenSSL::PKCS5
+rescue LoadError, NameError
+ $stderr.puts "Skipping KeyGenerator test: broken OpenSSL install"
+else
+
+require 'active_support/time'
+require 'active_support/json'
+
+class KeyGeneratorTest < ActiveSupport::TestCase
+ def setup
+ @secret = SecureRandom.hex(64)
+ @generator = ActiveSupport::KeyGenerator.new(@secret, :iterations=>2)
+ end
+
+ test "Generating a key of the default length" do
+ derived_key = @generator.generate_key("some_salt")
+ assert_kind_of String, derived_key
+ assert_equal OpenSSL::Digest::SHA1.new.block_length, derived_key.length, "Should have generated a key of the default size"
+ end
+
+ test "Generating a key of an alternative length" do
+ derived_key = @generator.generate_key("some_salt", 32)
+ assert_kind_of String, derived_key
+ assert_equal 32, derived_key.length, "Should have generated a key of the right size"
+ end
+end
+
+end
Please sign in to comment.
Something went wrong with that request. Please try again.