MessageVerifier#verify raises InvalidSignature if the signature is blank

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

activesupport/lib/active_support/message_verifier.rb

@@ -26,6 +26,8 @@ module ActiveSupport
     end
     
     def verify(signed_message)
+      raise InvalidSignature if signed_message.blank?
+
       data, digest = signed_message.split("--")
       if secure_compare(digest, generate_digest(data))
         Marshal.load(ActiveSupport::Base64.decode64(data))

activesupport/test/message_verifier_test.rb

@@ -18,6 +18,11 @@ class MessageVerifierTest < Test::Unit::TestCase
     assert_equal @data, @verifier.verify(message)
   end
 
+  def test_missing_signature_raises
+    assert_not_verified(nil)
+    assert_not_verified("")
+  end
+
   def test_tampered_data_raises
     data, hash = @verifier.generate(@data).split("--")
     assert_not_verified("#{data.reverse}--#{hash}")