Use an options hash to specify digest/cipher algorithm and a serializer for MessageVerifier and MessageEncryptor.

activesupport/lib/active_support/message_encryptor.rb

@@ -13,12 +13,15 @@ class MessageEncryptor
     class InvalidMessage < StandardError; end
     OpenSSLCipherError = OpenSSL::Cipher.const_defined?(:CipherError) ? OpenSSL::Cipher::CipherError : OpenSSL::CipherError
 
-    attr_accessor :serializer
+    def initialize(secret, options = {})
+      unless options.is_a?(Hash)
+        ActiveSupport::Deprecation.warn "The second parameter should be an options hash. Use :cipher => 'algorithm' to sepcify the cipher algorithm."
+        options = { :cipher => options }
+      end
       
-    def initialize(secret, cipher = 'aes-256-cbc', serializer = Marshal)
       @secret = secret
-      @cipher = cipher
+      @cipher = options[:cipher] || 'aes-256-cbc'
-      @serializer = serializer
+      @serializer = options[:serializer] || Marshal
     end
 
     def encrypt(value)
@@ -30,7 +33,7 @@ def encrypt(value)
       cipher.key = @secret
       cipher.iv  = iv
 
-      encrypted_data = cipher.update(serializer.dump(value))
+      encrypted_data = cipher.update(@serializer.dump(value))
       encrypted_data << cipher.final
 
       [encrypted_data, iv].map {|v| ActiveSupport::Base64.encode64s(v)}.join("--")
@@ -47,7 +50,7 @@ def decrypt(encrypted_message)
       decrypted_data = cipher.update(encrypted_data)
       decrypted_data << cipher.final
 
-      serializer.load(decrypted_data)
+      @serializer.load(decrypted_data)
     rescue OpenSSLCipherError, TypeError
       raise InvalidMessage
     end

activesupport/lib/active_support/message_verifier.rb

@@ -26,12 +26,15 @@ module ActiveSupport
   class MessageVerifier
     class InvalidSignature < StandardError; end
 
-    attr_accessor :serializer
+    def initialize(secret, options = {})
+      unless options.is_a?(Hash)
+        ActiveSupport::Deprecation.warn "The second parameter should be an options hash. Use :digest => 'algorithm' to sepcify the digest algorithm."
+        options = { :digest => options }
+      end
 
-    def initialize(secret, digest = 'SHA1', serializer = Marshal)
       @secret = secret
-      @digest = digest
+      @digest = options[:digest] || 'SHA1'
-      @serializer = serializer
+      @serializer = options[:serializer] || Marshal
     end
 
     def verify(signed_message)
@@ -39,14 +42,14 @@ def verify(signed_message)
 
       data, digest = signed_message.split("--")
       if data.present? && digest.present? && secure_compare(digest, generate_digest(data))
-        serializer.load(ActiveSupport::Base64.decode64(data))
+        @serializer.load(ActiveSupport::Base64.decode64(data))
       else
         raise InvalidSignature
       end
     end
 
     def generate(value)
-      data = ActiveSupport::Base64.encode64s(serializer.dump(value))
+      data = ActiveSupport::Base64.encode64s(@serializer.dump(value))
       "#{data}--#{generate_digest(data)}"
     end
 

activesupport/test/message_encryptor_test.rb

@@ -52,9 +52,9 @@ def test_signed_round_tripping
   end
   
   def test_alternative_serialization_method
-    @encryptor.serializer = JSONSerializer.new
+    encryptor = ActiveSupport::MessageEncryptor.new(SecureRandom.hex(64), :serializer => JSONSerializer.new)
-    message = @encryptor.encrypt_and_sign({ :foo => 123, 'bar' => Time.utc(2010) })
+    message = encryptor.encrypt_and_sign({ :foo => 123, 'bar' => Time.utc(2010) })
-    assert_equal @encryptor.decrypt_and_verify(message), { "foo" => 123, "bar" => "2010-01-01T00:00:00Z" }
+    assert_equal encryptor.decrypt_and_verify(message), { "foo" => 123, "bar" => "2010-01-01T00:00:00Z" }
   end
 
   private

activesupport/test/message_verifier_test.rb

@@ -45,9 +45,9 @@ def test_tampered_data_raises
   end
   
   def test_alternative_serialization_method
-    @verifier.serializer = JSONSerializer.new
+    verifier = ActiveSupport::MessageVerifier.new("Hey, I'm a secret!", :serializer => JSONSerializer.new)
-    message = @verifier.generate({ :foo => 123, 'bar' => Time.utc(2010) })
+    message = verifier.generate({ :foo => 123, 'bar' => Time.utc(2010) })
-    assert_equal @verifier.verify(message), { "foo" => 123, "bar" => "2010-01-01T00:00:00Z" }
+    assert_equal verifier.verify(message), { "foo" => 123, "bar" => "2010-01-01T00:00:00Z" }
   end
 
   def assert_not_verified(message)