def build_authenticated_parameters email, user_identifier, options
      build_request(email, user_identifier, options).tap do |request|
        request['digest'] = digest_request(request)
      end
    end
def build_authenticated_parameters email, user_identifier, options
      build_request(email, user_identifier, options).tap do |request|
        request['digest'] = digest_request(request)
      end
    end
Private: Build a signed hash of parameters for redirecting the user to checkd.in.

 Returns a hash including a secure message digest and the current timestamp