lib/layouts/fie.html.erb
<span fie-body='true'>
<%= yield %>
<% assigns.map do |assigns_name, assigns_value| %>
<% unless assigns_value.nil? || assigns_name == :marked_for_same_origin_verification %>
<% encryptor = ActiveSupport::MessageEncryptor.new Rails.application.credentials[:secret_key_base][0, 32], Rails.application.credentials[:secret_key_base] %>
<span fie-variable='<%= assigns_name %>' fie-value='<%= encryptor.encrypt_and_sign Marshal.dump(assigns_value) %>'></span>
<% end %>
<% end %>
<span fie-controller='<%= params[:controller] || @fie_controller_name %>' fie-action='<%= params[:action] || @fie_action_name %>'></span>
</span>