module ActionDispatch::Cookies::VerifyAndUpgradeLegacySignedMessage

def initialize(*args)

:nodoc:
opportunity to detect and migrate legacy cookies.
(de)serialization step within the cookie jar, which gives us the
to the Message{Encryptor,Verifier} allows us to handle the
Passing the ActiveSupport::MessageEncryptor::NullSerializer downstream 
def initialize(*args)
  super
  @legacy_verifier = ActiveSupport::MessageVerifier.new(@options[:secret_token], serializer: ActiveSupport::MessageEncryptor::NullSerializer)
end