I am trying to have shared cookies between Rails 3 and Rails 4.1 apps. The problem is that the Rails 3 cookies are just base64 encoded, but the Rails 4.1 cookies are encrypt
Have you tried unsetting secret_key_base and setting secret_token to the same value you're using in your Rails 3 app? This might not work, but I don't see anything in the 4.1 upgrade guide to suggest it wouldn't.
If that doesn't work, the options I can think of: